Actually, only Sleen is useless towards the end of the game, but he's very helpful at the beginning with his "hellish formation" :).
Posts from Casket of Fury
Most useful Spirit of Vengeance:
Do you mean a mod? I know of a mod like that, but it only increases the maximum level by 10 ;). Hmm, something's not right here...
In general, only Slim is useless in the late game, but he's very helpful in the early game with his "hellish ambush" :). Zerok, as I said, has very good "stone spikes," Lina has "ice ball" and "Gizmo," and the Reaper has good skills overall, although "rage collection" is less useful.
The Reaper's skills are good, but it requires a lot of rage. I don't use Lina much in the late game, but Zerok and the Reaper are in demand. Although I only use "stone spikes" with Zerok...
Added 1 minute ago
I also like the armor. Although it doesn't absorb a lot of damage, it guarantees that one enemy attack will fail against this unit :)
Демократия есть одурачивание народа при помощи народа ради блага народа.(Уайльд Оскар)
But regarding the topic, when playing as a Paladin, I messed up with Zerok by leveling up his Rain ability; in reality, I don't even need it, and some other abilities of other spirits aren't that useful either, but since that's the case, they're all useful in their own way; Reaper is just the most overpowered, especially in the late game, and not just in the late game. And in general, you need walls, the Orb, Gizmo is often useful, and energy-generating creatures... Well, Time Warp was one of the few ways to save a Black Dragon, for example, so there's not much to comment on there. And in general, Lina is very helpful, and unlike the Reaper, the cost of Fury for her abilities is quite reasonable. The first time I played as a Warrior with 2 stacks of Faeries, I threw one of the stacks, along with a Ruby of Anguish, into a pile; they were, I think, Lake Faeries, they created Mud, and then they returned. :)