more ideas for the Sylvan faction:
1. War Fury: +3 to Attack and Luck if there is an enemy hero within the hero's movement range. Skills: Leadership, Luck
2. Vampire Slayer: deals triple damage to vampires and creatures under the Vampirism spell from Sylvan units (I think this is technically not feasible, but who knows). Skills: Light, Wrath
3. Silvanne's Devotee: all units in the hero's army are always under the effect of the Temple of Mother Earth (I think even technically this is simple). Skills: Defense, Resilience
4. Blood Revenge: if the enemy hero is a Necromancer, then Magic and Attack are multiplied by (1.5 + 0.02 * hero level) (I think something like this: if hero(count_player) = warlock then first combat +SpPw=0.5+0.02*level; +Attack=0.5+0.02*level. this is General, I don't know how to correctly write programs and operations for mods, this is in the sense of the principle). Skills: Attack, Magic (you can use Education instead of Magic)

Added 4 minutes later
similarly for the Tower faction, like the last one for the Elven faction: only if the hero is an Avenger, and Knowledge and Defense are increased. Skills: Magic, Defense