What are the most dangerous unit combinations in Dungeon?

Sorgall doesn't add attack and defense to riders; it only increases the damage from the bite. Erin's ability doesn't affect regular attacks; it only affects spells, and the chance of it triggering should be the same for all spells.

I apologize for the outdated information. In 3.0, Sorgall indeed significantly increases the damage from the bite, making the combination even more dangerous. However, they still react more to lightning (maybe the elements are the same?).