Created back when I played it and was hoping to see Naga as the new mystery fifth Horde race:
Sea Witch
Races: Naga, Undead
Weapons: Bows, Staffs, Wands, Tridents
Talent Trees: Negation, Preservation, Water Familiars
Transfer Blessing- Moves all buffs on one target to caster.
Gather Blessing- Same as Transfer Blessing, but moves all buffs on any character within a 400 radius to the caster.
Transfer Curse- Moves all debuffs on caster to one target.
Gather Curse- Same as Transfer Curse, but moves all debuffs on any character within a 400 radius to the target.
Purge- Removes all buffs and debuffs on one target.
Tornado- Removes one target from battle for 4 seconds. They cannot move, attack, or be attacked.
Spell Eater- Summons 'Spell Eater' orb as a pet. The next 2 Spells used by anyone within a 300 radius are absorbed, and half the mana/energy/rage used to cast them sent to the Sea Witch as mana.
Ability Eater- Same thing as Spell Eater, except for physical abilities.
Oxygen Bubble- Generates a 400 radius bubble around caster while underwater. All allies within the bubble cannot drown.
Time Lock- Resets one target to whatever status and HP they were in 5 seconds ago. This can be used as a revive if the character died less than 5 seconds ago.
There's more than these but you get the idea. Basically a 'meta' anti-caster hero who can also generate an 'Eater' orb, Mur'gul or another sea creature as a pet. Would likely include variants of Medusa's 'Mana Shield' from Dota as well.