Amazing game. Some fun combos I've found:
Twin Daggers + Blue Skink copying Valkyrie. Hexia never stood a chance... Also got me the 4-revive achievement.
Siphon + Poseidon's Trident. Works best with Enchanter, but any side that "Adds self-shield/self-heal" will serve to get your engine going, Twins are also a plus
Damage combos? What are they?