HFEO – heroes for everyone.

Yes, but which one? Changing his existing specialization is not a problem, but what would you like to see him have?

Honestly, I have no idea. I just really liked that you gave Kha-Belekh the specialization with Hellfire (it really suits him), Belket the Death Lord, as he is the first necromancer, and Michael and Uriel an ability related to the guardian angel.
But I have no idea about Tieru. As far as I know, Swift Striker is the most overpowered ability in multiplayer, and he had it in the scenario, but according to the lore, he is a dragon knight, so I'm not sure what would suit him.