Minecraft wiki entry for Combat, associated text: A blaze suffers damage from snowballs, and would be damaged by water if there was any in the Nether. Alas, snow golems do not survive in the Nether unless immediately provided with a potion of Fire Resistance or possibly a Regeneration potion. However, player-thrown snowballs are still a viable tactic. Due to their ease of acquisition and infinite supply, snowballs can be considered superior to archery for battling blazes. Though they can't be used to damage other kinds of mobs, carrying a few stacks of snowballs while exploring nether fortresses is an excellent way of repelling unexpected waves of spawned blazes. In addition, other mobs like wither skeletons and magma cubes can often be knocked off the high fortress bridges with snowballs, adding further usefulness.