Favorite hero from Dungeon.

Sanitar doesn't have an immediate buff, but Plague undoubtedly consumes much less mana in the end. However, the ability might not trigger, and casting Plague requires a turn, and it doesn't take effect immediately. Moreover, dark magic isn't the best solution for a Warlock; everything is geared towards chaos, and combining dark and chaos is not the best choice. Firstly, it will take a lot of experience, and the benefits won't be significant. Secondly, in battle, you either need dark magic or chaos magic; I don't think it's worth taking both.
P.S.
Although I consider this hero weak, I still like him; I played with him before and still play with him now. He probably has the most interesting (but not the strongest) ability in the game, but still, he can't compete with Sanitar, the Blood Queen, or the Lady of the Wood.