Only some suggestions for abilities:
-Spellcrit (% chance for double damage on spell)
-Normal Things ( Int, Str,Agi,Hp,Mana,Attackspeed,Movementspeed etc,)
-Spell avoid (% chance to avoid a spell)
-% bonuses like 10% damage etc (good for highlvl items)
-% chance to cast a certain spell when hited
-% chance to kill a non boss after a hit
-% chance to block X damage
-% Damage reflected after attack
-% chance to heal X hp or mana on your self on attack / when attacked
-Active Skills(remember, only one!) but it shouldnt be a damage making spell
-Aoe damage
-% chance for ministun
-Poison damage( damage over time)