hmm . . . let's say repair bots have about 14000 HP at the time snowman spawn, which is around 13~15 minutes remaining time. The Area of Effect attack that the snowman has only deals around 3200~3400 damage. Not only the repair bots have fair HP regeneration, it's not likely that 4 snowman use the ability constantly, while 3~4 X mode is just an optional bonus or challenge, technique/strategy should be applied accordingly/relatively. That being said, you can blink those repair bots away or protect them inside bunker when snowman or water bosses come, or you can buy extra tree of vigors; ultimately, kill them fast enough so you don't have to worry much and keep the loss at minimum. Meantime, "stalling technique" is often not encouraged but cannot be avoided easily while playing multiple bosses mode on higher difficulties. Snowman(s) have lower frequency to use AOE ability when it's not being attacked or are wandering far behind other bosses, if you are player like me to stall, I tend to buy at least a magma fist + cursed larceny and have my walls ready before I plan to clear the bosses around 6~10 minutes remaining time. By that time, snowman(s) get killed easily even on nightmare mode. Also, Stun ability of Fire lord bosses is more like a reflex, I agree that the frequency of stun is annoying, but bosses have to be unique, you don't get permanent stun =.=, so accept the truth. Fire lord have much less total HP like Water...element boss (cannot remember the name), and they possess special ability/designed targets + behavior to make the game more balanced. You are not likely to hate snowman as much on 1X boss mode and you only need to buy your units a few hp potions. I wouldn't enjoy the game much if bosses only have increased HP and damage... that would make the game meaningless as building lumber mills is all you need? =.= come on. Not many players complained that heroes shouldn't have much variation of abilities.