The Corsair doesn't attack monsters directly. Instead, he scatters bombs randomly across the battlefield. The bombs explode and inflict area damage when hit by a monster. Depending on the unit's level, the Corsair has a chance to launch a Dangerous bomb which always inflicts critical damage, and each explosion increases the damage inflicted on enemies hit by all bombs.

the mana power-up is changing the way Dangerous bombs. In active mode, they move towards the monster portal. In passive mode, they become immobile.