Heroes 5.5 WarGame Edition - Tactical Edition.

Besides, considering how powerful he is (always 100% drain in WGE), the drain effect itself is the main thing.

Nevertheless, a temporary transformation into undead occurs, but on the other hand, this is not raising from the dead as undead, but a temporary transformation, i.e., if you approach it from this angle, you can avoid linking it to necromancy (then you need to call it something else, for example, "Aspect of Death").

In general, as I understand it, your position is that vampirism should be banned for everyone except necromancers, but this decision is unlikely to be acceptable to many other players in PvP, because it narrows tactical possibilities.

I agree with that, but it seems a bit unfair to other schools because darkness is already incredibly strong in terms of mind magic and is advantageous in any game length (unlike chaos), and here there is also the possibility of removing the most terrible spells, endowing with temporary immunity to them. In this regard, I really liked Heroes 4:
1) Magic of Life:
- allows you to remove debuffs from yourself (strong side)
- does not allow you to remove buffs from the enemy (weak side)
2) Magic of Death:
- allows you to remove buffs from the enemy (strong side)
- does not allow you to remove debuffs from yourself (weak side)
3) Magic of Order
- allows you to remove debuffs from yourself and buffs from the enemy (strong side)
- does not allow you to remove only buffs from the enemy and only debuffs from yourself, removing everything at once - both positive and negative effects (weak side)