Along with my previous suggestion with the Cold Iron Vanquisher, I recently thought of yet another unique ability that might provide Big Angry Bomb with a buff:
Big Angry Bomb has its Damaged Decreased slightly but has a unique ability of increasing damage based on how many enemies are within its Blast Radius. Basically, for every monster within its blast-radius upon detonation, it increases the base damage by 2% for every enemy after 1.
This would provide yet another uniqueness to something that is rarely used within the game and give it new life.
Or make it increase your damage when you have half or less of health. Because it's Big ANGRY Bomb, right?
But I liked your idea too.
+1