NHF – new heroes for Heroes V 3.1.

As a novice modder, I can only suggest ideas, and here's one that just came to me: a powerful attack – a forest elf with a primary ability that, before the battle begins, paralyzes a certain number of units with roots for a certain number of turns. This also grants standard bonuses to the affected units, such as the number of turns, the number of units entangled in roots, and bonuses to the units themselves, all depending on the level.
We could also change the bonuses for the skill tree for added interest, so instead of the usual defense and attack, we could use speed and initiative, with a weak dependency on the level.