Absolute skills

I agree, there are three problems with obtaining the ultimate skill: time, the probability of getting the necessary skills, and the need to sacrifice good abilities. So, the question of the usefulness of developing necessary abilities is very relevant. In my opinion, fighting to the last is quite good. After all, the living don't have ghosts, which you can easily use to protect skeletons from large, high-level creatures. And having one unit that always survives is a serious tactical advantage. And the subsequent solid defense is also not useless. It's a pity, of course, to give up evasion, but it's not critical.