Hellboy seems to never drop practically being invunrable or healing at times, has a connection to gods (hell he can cast some cleric type spells), uses all sorts of weapons or his fist, is very random in combat.
Hellbred Crusader. With a ancestral relic gauntlet.
You will be a juggernaught.
Go for Master of 9 or whatever to choose some abilities from desert wind for embracing your inner fire at higher levels.
If the book of 9 rorts is not allowed.
CG. Monk 2/Cleric 4 (fire or luck and destruction.. to a chaotic neutral force not a god)/Sacred Fist should do it pretty well if at 1st you take improved natural attack and have the visual of it upsize your fist.
If your DM is on board you can then level in entropomancer with your fist being the focus for the 'shard of entropy' (it makes for better damage but means you have to be in melee to attack and cannot get free attacks as a move action. Its also pretty cannon for your fist to be the focus of your power over spheres of anihilation.