Weapon X since he's a pain as a BG defender and would benefit the most from rank 4. Doom and Hulkling would also be great but it's something about a man in his undies with claws sticking out of his hand with a menacing look that you can't ignore.
Doom, Hulkling, Gorr or AA would all be great choices. Doom has got it all: good prestige, high attack and is a great defender as well. Hulkling is also an all rounder champ, being a great attacker and defender. Gorr and AA are all great nukes, and can finish BG rounds extremely quickly. It just depends on what you are going for with this rank up
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