hyena's!

[Vilk]

Yes? So you keep your stack at 60/70% of its max? Then it's a stack weaker than most at 90/100%

EDIT: A good point about using both thorns is that Thorns Sprout could be used to keep stacks at a not too low level. Not cool it's so random.
Another point is I feel that at impossible level, constant loss even with cheap units is big penalty because there's very few gold and its best to keep as much than possible to buy more items.