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A fortress survival guide about how to become a legendary lumberjack

By Erdam, a Clan SHS member

(last update : 19/07/2013)


The purpose of this guide is to share with all players my personal experience about how to be an efficient lumberjack in Fortress survival (FS). As anyone knows, producing lumber in FS is very important, particularly in difficult modes as wood is fast necessary to survive. You can consider this guide as a pro guide with the best techniques generally used by real pro gamers. The whole knowledge in this guide allow you to harvest wood as fast as possible in team base games and to become a great support player for your team and not a fag who can't feed properly your hungry mates crying "wood !" every 10 seconds...

To exploit the full potential of this guide, you have to be able to pick the alchemist hero Attached Image: alchemist.png (level 11 minimum) and it is even better if you have an higher rank which means more mana regeneration. However, i'll give some advice for lower ranked players which need to take the lumberer position.

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Mills characteristics

Mills comparisons :

- Lvl 1 mill : 1Lumber (L) /40seconds (s) = 0.025L/s

- Lvl 2 mill : 1L/20s = 0.05L/s
total cost: 5 wood

- Lvl 3 mill : 2L/20s = 0.1L/s
total cost: 15 wood

- Lvl 4 mill : 3L/12s = 0.25L/s
total cost: 55 wood

- Lvl 5 mill : 11L/10s = 1.1L/s
total cost: 220 wood
Comparison : 4 Lvl 4 mills = 12L/12s = 1L/s

- Lvl 6 mill : 13L/5s = 2.6L/s
total cost: 440 wood
Comparison : 8 lvl 4 mills = 24L/12s = 2L/s

- Lvl 7 mill : 22L/2s = 11L/s
total cost: 1760 wood
Comparison : 8 lvl 5 mills = 88L/10 = 8.8L/s

The interesting thing you can notice from the mills characteristics is that higher level mills produce more lumber per second than lower level mills. However, taking into account their price, you can notice that the level 7 mill isn't the most profitable.

Explanations : By using a rule of 3, we can determine for each type of mill the price needed to obtain an income of 1L/s . After this, it is possible to compare the different mills taking into account the price as the limiting factor.

- Level 2 mills : 1 level 2 mill costs a total of 5 wood and provides an income of 0.05L/s.
rule of 3 : (1L/s x 5 wood) / 0.05L/s = 100 wood (it costs 100 wood to obtain an income of 1L/s with level 2 mills).

- Level 3 mills : 1 level 3 mill costs a total of 15 wood (5+10) and provides an income of 0.1L/s.
rule of 3 : (1L/s x 15 wood) / 0.1L/s = 150 wood (it costs 150 wood to obtain an income of 1L/s with level 3 mills).

- Level 4 mills : 1 level 4 mill costs a total of 55 wood (5+10+40) and provides an income of 0.25L/s.
rule of 3 : (1L/s x 55 wood) / 0.25L/s = 220 wood (it costs 220 wood to obtain an income of 1L/s with level 4 mills).

- Level 5 and level 6 mills : No meaning here as level 5 mill upgrade doesn't costs anything, it is a part of a level 7 mill and it is relatively symply worse than a level 7 mill. Level 6 mill is worse than a level 7 mill too because it is less profitable and you need more time and space to win the same income than with a level 7 mill.

- Level 7 mill : 1 level 7 mill costs a total of 1760 wood (32x5+32x10+32x40) and provide an income of 11L/s.
rule of 3 : (1L/s x 1760 wood) / 11L/s = 160 wood (relatively, it costs 160 wood to obtain an income of 1L/s with level 7 mill).

Conclusion : If level 1 mills can be upgraded, you should do it first because the level 2 mills are the more profitable early. Then focus on level 3 mills when all mills are are level 2 or under construction. With this same principle, start making level 4 mills and focus on 1 level 7 mill only when all mills are level 3 or under construction. The pictures below illustrate these steps.

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Step 1 : upgrade all your level 1 mills Step 2 : upgrade all your level 2 mills Step 3 : focus on 1 level 7 mill

Upgrading time of mills :

upgrading time from lvl 1 to lvl 2 mill : 70s

upgrading time from lvl 2 to lvl 3 mill : 120s

upgrading time from lvl 3 to lvl 4 mill : 185s

Notes : You don't earn any wood during mills upgrades. As the upgrading time increases from level 1 mill to level 3 mill, it confirms that level 2 mills are the most interesting mills taking into account their price (as explained above) and their upgrading time from level 1 mills (which is faster than others).

Factories characteristics

Construction time of a factory : 25s

Note : It takes only a few minutes to make a decent factories area (15-25 factories) which is very helpful to create mills as fast as possible. You lose some time to create your factories area but you'll win time after for the whole game !

Construction time of a lvl 1 mill with factories :

Factories are essential to build fast mills and the more you have, the faster you are ... Here are the times necessary to build a single level 1 mill depending on the number of factories helping :

- 0 factory : 35s
- 1 factory : 21s
- 2 factories : 16s
- 3 factories : 13s
- 4 factories : 10s
- 6 factories : 8s
- 8 factories : 7s
- 10 factories : 6s
- 12 factories : 5s

A good lumberer should try to have a minimum of 6-8 factories helping the construction of 1 mill. Having less factories means lose many time per mill construction. With 10-12 factories (the maximum possible), i guarantee you can build easily more than 200 mills during the whole game.

Factories areas :

Here are 2 examples of the best possible factories areas for 2 great bases : "Summer Cottage" and "The Courtyard". The left picture simply shows the best factories area with the most number of factories helping the mills construction.

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Summer cottage base The Courtyard base

Explanations : I'm pretty sure some guys will ask me "Why these areas are the best possible ?" and "How factories exactly works ?". Well, i didn't find the mathematic rule concerning the helping rate of factories but i have noted precisely their efficiency. Concerning the best possible areas, the picture below explain how a mill named "A"can be helped by 12 factories at the same time. You can try if you want but it is impossible to have more than 12 factories, and you need a big place for this kind of factories area. Generally, it belongs to you to find the best factories layout, depending of the available space (for example, you can't put enough factories in "The Courtyard" base but an average of 8 factories per mill is still good, as shown in the top right picture).

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The mill "A" helped by 12 factories

If you aren't familiar with these factories areas, i advise you to analyse the above pictures and to count the number of factories helping each mill (12-10-10-11 for the Summer Cottage picture and 9-8-8-9 for the Courtyard Picture).

Conclusion : always try to make the best possible factories area. If you have enough space, you should try to make the best area like above or something near. If you haven't, try to make an area where mills are helped by more than 6 factories (which is often possible).

Use of Alchemist(s)

After reading the "Factories characteristics" part of this guide, i'm sure some guys could ask me : "Why there are always 4 mills inside the factories area in the pictures above, and why not 3,5 or 6 mills ?". The answer depends on your way of playing (with or without an alchemist hero , with or whithout a lot of space, etc...). The general purpose is to never be out of mana with your alchemist(s), so manage your mana pool the best you can. If you are running out of mana, your lumberer activity will just stop and it isn't a good thing...

The "Area Transmutation" spell costs 90 mana and you have to use it potentially every 25-30 seconds if you build 4 mills each time. The survivor rank determines the alchemist hero mana regeneration, and according to my experience, a level 25 ranked player have got a mana regeneration of 100 mana every 30 seconds so there is no problem for him to perma transmute mills if he builds 4 mills at the same time with 10-12 factories helping.

However, a level 11 ranked player will have some troubles as his mana regeneration is much lower. To solve this problem, the best solution is to build 5 or 6 mills each time as illustrated below (not in length or the area of effect of the "Area Transmutation" spell will not be enough), but you can reduce the number of factories too if it is interesting to save space.

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From 4 to 6 mills in a factories area

Now, if you can't or if you don't want to pick the alchemist hero, you can still be a quite good lumberjack for your team (or if u play solo) but with more limitations. Mercenary alchemist can be claimed for free on the map or it costs 80 wood and you need to have a mercenary HQ (it means construction time and an additional 30 wood). Furthermore, as its mana regeneration is of 75 mana per minute only, it can be a good idea to manage your mana pool as i explained above, to buy some mana potions (250 mana for 30 wood) available in an Item Vendor , or simply to make 2-3 mercenary alchemists (which is the best solution according to me over the long term).

The lumbering priorities :

1/ make sure your survivor is always building mills

2/ upgrade your mills as soon as possible and focus on 1 future lvl 7 factory each time

3/ drop your shrinked lvl 1 mills

Note : Respect these priorities (especially the 1st one) and you are on the right way.

General tips

- You don't need full hp factory to make lvl 7 mill. Concerning myself, i'm used to build this factory when lvl 5 mills are soon ready. I've saw many guys who lost precious early time to make first full hp factories instead of focusing on building mills...

- When you make lvl 5 mills, take care to select manually the good 4 lvl 3 mills u want to combine them into a lvl 5 mill (use the "Shift" key). If you select automatically all lvl 3 mills (double click and upgrade of 12 mills), it will be an epic fail when random created lvl 4 mills will be combined into lvl 5 mills.This fail illustrated below is annoying because it means waste of precious time and mana.

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- Take care to protect your mills from ranged attacks. The best solution is to make mills not close to the cliff or just to upgrade the "strenghtened utilities" research at the cost of 20/40/60 wood to upgrade the hp of your mills by 2000 each time (the lvl 1 upgrade is generally enough to have a good security and to have time to react with heroes if troubles).

- Take care to protect your mills from Deadban Khan earthquake (boss spell).Just upgrade the "strenghtened utilities 1 " (20 wood for +2000 hp) against this threat.

- It's better if u think about providing space for your future lvl 7 mills. A good lumberer need to know exactly where he will put his mills before starting to build. Furthermore, if there are others lumberers who need to share the space of a same base (or a chain base), it is better to define the space allowed for each guy to build harmoniously.

- Don't waste any time early game with your worker if u are lumberer. It is very important to launch as fast as possible your lumber activity as the defender guy will need fast wood to secure the base defenses with vital research and upgrades. Besides, wasting some precious minutes early game for lumberer guy means loosing some hundreds or thousands of wood amount at the end of the game...

- Don't forget to prepare 1 another mill lvl 4 for a future goldmine . If u don't think about it early, u will loose many time due to the mills upgrading time.

- When your first lvl 7 mill is rdy, don't transmute it yet if possible as the operation time to make this tiny lvl 7 mill is approximately 20 seconds. It means you will lose something like 220 wood (11L/s x 20s) which can be useful to have other lvl 7 mills as soon as possible, or to help the defender guy in case of emergency !
  • Nevo likes this

Author Credit: Posted By Erdam As Topic - 14/07/13

Re-Posted By Nevo As Guide - 10/06/15


Jul 14 2013 05:55 PM

Some VERY nice advice, ty  :D


i'm not sure about the focus on 1 lvl7 first tho..

Certainly. the rush to lvl5 mills should focus on one...

but before that i dont think so.. perhaps we should play together some game and test it side by side?  :)


reasons i think it is better to prefer upgrading lower level mills:

  • each higher tier gives LESS extra lumber per lumber invested (altho total production is indeed higher) thus you gain more income for same investment if you up low lvl mills
    • until lvl4 upgrade. lvl 5-7 have effectively 0 lumber cost. 
  • lumbers upgrading give no wood ( i know you know this.. but) the implication: you lose less income at the current moment by upping lower mills instead of high mills. this means you get more income in the near term which you can use to up other mills (thus this temp advantage is made permanent)
  • upping mills takes time, so by preferring to get first lvl7 without upping other mills at all you significantly delay the ready of second(and third ..) lvl7 mill.

we will never know the truth till 2 pro lumbers do this side by side.. but least we can rant bout it here  :P

Ok waffle,


Now u force me to put matchcraft on this guide to prove what i say ^^. Thank you very much !!!


Im' not sure 100% that i've got the truth but the fact i have never saw a guy faster than me, i'm quite sure focusing a level 7 mill is better.

I'm agree when u say u lose income at the current moment but i think it is still a profitable long term investment (which is the most important thing).


Just w8 a few plz for proves, i haven't finished yet this guide ^^.

Jul 14 2013 06:41 PM

maybe theres just really few pro lumbers to compete with u  :P


oh and one more tip to add..

these formations work best when you have alchemist hero OR custom hero with mass transmute.

regular alchemist unit's mana simply can't keep up with even much more basic factory patterns (i have out-used 3 alchs on smaller factory amplification than what you propose)


this guide presumes that pro lumber has some rank and can at least get alchemist hero (+ rank gives mana regen bonus for hero so you don't run out!)

If you are less than lvl11 and need to take position of lumberer then ..

  • Ask to get control of your team mates hero if it has mass transmute. this will be almost as good as your own custom hero but will drop minified mills on ground (can add up to a lot of time wasted if you place them after every cycle, keep in mind the first rule: keep worker buildings mills as much as possible, and avoid worker idle time)
  • always use hero to place mills (or any unit EXCEPT the worker)
  • if you can't get control of transmute-enabled-hero then increase the amount of mills you build in one batch. this reduces the rate at which you consume mana (as mana will most likely be THE limiting factor) make a factory to build 6(or more, as long as you get to transmute them in a single cast of the spell) mills instead of four. keep in mind this will reduce your factory amplification ( pro guy with many alch units and regular 4-spot mill-factory will pwn you later in the game) (80w for alch is actually very cheap since pro-s make over 100k lumber per game, its just hard to get many of them in the first minutes of the game)

Btw, thx again for the nice guide.

and thx for taking the trouble to actually test and find out which is faster  :)

I like the guide, but I have to disagree with focusing only on one t7 at a time. Having to wait 6 minutes and 15 seconds for each t7 to start upgrading from lvl 1 mills is a lot of time lost. I think that getting all of them to level 3, and then focusing the lvl 4->5 upgrades on one at a time would be faster, and the mills would produce an overall higher amount of lumber in the meantime.


I'll give it a shot though, just to see if I'm wrong.


Also, like waffle said, you should give some advice for people that can't access the alchemist hero, or can't use him because they need a more damage based hero. Someone soloing in 6.3 would need a different hero, since the alchemist uses magic damage and the final bosses go immune to magic when in their avatar form. 

Nice guide!


I think it gives more lumber at the end of the game if you focus on upgrading the first t7 before other stuff. I tried both ways a bunch of times in 6.10 ( the build times have changed slightly since then). Like you said you will have less lumber early on but end up with a bit more. It doesn't really matter that much either way, it's a small difference. The much more important thing is to build the most t1 mills possible, as this is the only limiting factor after the first t7 is done, which is like 3/4 of the game.


Also, if you factor in the opportunity cost of lost production, the total costs are:


t2 = 6-7 wood

t3 = 22-23 wood

t4 = 80-83 wood


After t4, it depends on how close together you complete the fusing mills and is impossible to give a general value.


If you don't have a transmuting hero, get a large base (at least the size of the Summer Cottage). Make rows of factories with 4 spaces in between, and build full sized t5 lumber mills in between the factories. You can upgrade those to t6 for 320 lumber. One mercenary alchemist can fully handle all the necessary transmuting. I have made over 100k lumber making only t5->t6 solo with a commander.


Totally unrelated, but how much down time does your peasant have in between batches with only 4 spots to build mills? I usually make 8 spaces so there is no down time, but then you have to make 16 extra factories with 4-5 factories working on each. 


Well i think there is maybe 3-4 sec of down time. I never make more than 4 spaces as more space is needed and most of the time it becomes hard after to manage space inside common bases. I just think 4 spaces is the best compromise ...

Jul 15 2013 05:59 AM

i commonly have anywhere in between 0.5-2s down time.


it takes a moment for mass transmute to take effect.. so i usually cast it bout .5 sec early.. and then already select builder so i can place next 4 mills.

    this has the risk: if you cast too early your last mill will be left unfinished and cost you anywhere between 2-10 sec depending if you are prepared for such event.

basically the only factor you should care about is keeping your worker occupied as close to 100% of the time as possible (once you have a good factory pattern)

the other things are all minor in comparison.


i usually use a 10 factory pattern for sake of saving space (6 or 8 factories per mill depending on location..) (spec in team bases) 

having low worker down time can compensate for slower building .. (and higher factory amplification can compensate for slow mouse..) but when you DO have the space.. try to have a little better amplification..


unfortunately most of the mills on a high amplification base can only help build 1 mill and take some time to build..

so if you need early lumber.. you can delay building them(factories that dont have direct contact with a mill) a little to get first lumber earlier.. (will lose u end game lumber tho)

Yeah, i agree


It is just we have all mass spikes when playing, that's why i don't speak about the best possible efficiency but i always add a few seconds needed. I don't want to give false hope to players.


More important guys, i have made some tests with and without lvl 7 focus. And as i finally expected after seeing good arguments, focusing mass levels 3 seems to be the best way. 


I made 2 games with the 2 differents ways. I began to create mills at 50min, i reached as fast as possible 3 lvl 7 mills whithout creating other mills after the first 96 (3x32) and upgrading other mills during last level 7 upgrading.


Here are the results of 2 test games : 


Game 1, Focusing 1 level 7 then another and using all possible wood to up mills until level 3 of the 2 last levels 7 :

3rd level 7 mill reached at 30min20sec with a total produce of 8570 wood.


Game 2, Up all mills level 2 then level 3 as fast as possible. When extra wood, then i focus on  level 4 mills to prepare the 1st level 7 mill, then the other etc.

3rd level 7 mill reached at 30min20sec (lol ...) with a total produce of 8920 wood (+350 total wood).


Conclusion : make mass lvl 3 mills first as krehara and waffle said.


However, even if it is more efficiency, i have found harder to manage this technique as you need all the time to upgrade mass mills. Maybe more difficult with spikes but all pros have to use it i think.

Jul 15 2013 04:14 PM

YAY.. just did a game with 266,700w team inc..  :D

(till eternia finally killed us..)

(was the only one who built any mills)

Baby Michael
Jul 15 2013 09:12 PM

That was a good game  :D


And good job on your guide, it's really nice!

8 Factories is my build... And i believe its fast..

not in building lumber mills but in producing

the explanation of mine is simple and not calculated

 > Why i prefer this that having that number of factories than the one suggested?

  - 8 repair factory is enough for me

  -  9~14 (the time used for building those is a waste)

     and i believe instead of using that time building another 5 factory should be used for mills

     ive been doing it since i become a 11 ranked and i believe im doing well

Jul 27 2013 03:35 PM

with 10 mills (5+5) you can get a significant increase already with barely any room waste. (33% extra repair rate from factories)

with a personal lumber total of nearly 280k (max diff) i can say that 1 mill less(or placed less than optimally, from a 8 mill formation id say you have crappy placement that already costs you) WILL have a very significant effect.

waffe, when did u reach that 280k lumber? by the time tyrant killed or in certain level of endless?thx

You don't need full hp factory to make lvl 7 mill. Concerning myself, i'm used to build this factory when lvl 5 mills are soon ready. I've saw many guys who lost precious early time to make first full hp factories instead of focusing on building mills...


Just want to confirm. You need to build the factory before the last lvl 5 lumber mill is complete or it will not transform.

Aug 25 2013 10:48 AM

yes, you need start construction of the repair before last lvl5 finishes upgrade.


280k was on eternia attempt it was the number that was left after eternia killed all my lumber production capacity.. 

( if you want comparable results then we would have to measure at the time when trojan spawns.. because all the following checkpoints change depending how fast u kill end bosses.


eternia attempts they usually die really fast tho

I propose this build could be more effective:

Sep 12 2013 08:01 AM

Nice , ty erdam for the advice  :D