Tim (Alliance ally <3>)                 Elusive + free recurring NCD = GOOD
Primalist Naseth (Alliance ally <6>)    Free recurring NCD + healing, awesome.  A bit expensive and weak, but still...
if bestowed-elusive, then these are practical:
    Adept Breton (Alliance Ally <2>)    1dmg to all opponents
    Melgwy Pingzot (Alliance Ally <2>)  5dmg to one <5>

Elithys Firestorm (Horde ally <2>)      Cheap and powerful, but needs help staying alive in mid/late game to do any damage.
Arnold Flem (Horde ally <4>)            1dmg to all opponents on death, good
Panax the Unstable (Horde ally <5>)     Situational (don't want any your guys out when he goes off), but can wipe out all allies, so...


Grimdron (Warlock ally <1>)             Obviously good.

Helmet of Ten Storms (Shaman <4>)       1dmg for 2res.  Great.  Unlike the fire helm, lets the hero also strike with a weapon.

Helm of Fire (armor <3>)                3dmg for 5res.  Great.

Netherwind Crown (Mage armor <3>)       1dmg for 1res.  Costs $16 though!!??

Skullflame Shield (armor <6>)           Stops people from attacking your hero!  Out of stock everywhere though... :(

Flame Wrath (weapon <4>)                Great.  Similarly, makes people hesitate to attack you.

Rod of the Ogre Magi (weapon <4>)       1dmg for 2res