Am I too late for hero spells?
Forsaken
Death grip- pulls target x/x/x distance and force him to attack hero.
Bone shield- deals x/x/x damage to enemies. Has x chanse to stun opponet.
Frost aura(passive) - every enemy melee unit that attacks any friendly units under this aura is slowed by x/x/x
Blood Boil- deals AoE dealing x damage and infacting targets with infaction on that field. Any target that dies with it is turned into zombie. Only infaction can be desabeled.
Blood elf
Hand of Salvation- gives x/x/x own health to friendly target
Exorcism- deals x/x/x DoT to single. If target dies it heals friendly units nearby or damages enemies by x/x/x.
Holy strike (passive)- target is healed by x/x/x with every attack. Works only on blood elf hero.
Retribution- standard pally ultimate
Garrosh
Berseker (auto cast)- deals x/x/x damage and is increased with every kill by x, but takes extra damage by x/x/x
Rally (passive)- increase damage and speed of friendly units by x/x/x
Mortal Strike- strikes single target dealing x/x/x damage and healing himself by x/x/x
Kor'kron- calls 3 elite kor'kron to die for him (very powefull grunts).
Baine
Mighty blow- deals x/x/x damage and pearce reduces enemy armor by x/x/x.
War stomp- standard TC abillity
Earhmother protection (passive)- reduces x/x/x harmful spells on him.
Ancestores guide (passive)-when low on health 2 invarnebul taurens come to aid for x time
Warlock
Necromancy- can raise 2 weak/avarge/strong skeletons from dead corpse (should not add damage like dark ranger. Just raise dead)
Fear- makes small/medium/big AoE that makes enemies lose control and run in fear for x/x/x.
Shadow embrace (aura)- increase regeneration by x/x/x (like arcane brilliance, only with health).
Animate dead- standard DK ultimate.
Hope I gave you good ideas and I'm not to late. Most of this I came idea trough WoW.

I have no idea for Vol'jin. I think original shadoe hunter is perfect.
Ps.
Lor'themar
Arcane blast- deals x/x/x damage to AoE and purging at a same time.
Farstreder ambush- all nearby friendly units become invisibul that last for x/x/x time. Disabeled when they attack or take damage.
Veteran trening (aura)- increase all melee damage attack by x/x/x (opposite from trueshot aura)
Phoenix strike- Unleash 3-4 Phornix in AoE that stuns and x damage all units in that AoE