I struggled for a long time to see the best way to use exploding dwarf. Once he gets up to Level 6 he is a beast. I am starting to experiment with him in tank position or last position.

In tank he might get the first shot on someone. If the other tank hit him first then retaliate is a great ability. Either way he will pierce two opponents at that point.

He is dead in the water if attacked with magic. Game over!