Ominas Crowe is a boss in Bravely Default, fought in the Ruins of Centro Keep. He has a variety of status effect spells at his disposal with the potential to cripple the party, along with his powerful Fire spell. Defeating him earns the party the Black Mageasterisk.
Compared to the orcs in the dungeon he is fought, Crowe is a bit easier to handle. White Mages will help keep his damage at bay. He casts Silence, but equipment can be found to prevent it. Monks can Default and then use Invigorate and attack, or simply attack. One can also use Freelancers as balance between healing with Treat and attacking. They can Default and perform both duties, just use Treat or simply attack, making the battle easier.
For future battles, Spiritmasters are recommended for healing and dispelling status ailments as well as nullifying Crowe's attacks. Otherwise, one can equip Flame Charms or the support ability Abate Fire to mitigate the damage of his Fira spells. He will also use Silence, Poison and Thunder on a single character for great damage, but the Performer's buffs and the Pirate's debuffs can mitigate the damage.
In the fourth battle onwards, he is often accompanied by Argent Heinkel who will block all single-target physical attacks. Therefore a good strategy is to make one character a Pirate and break Heinkel's defenses, followed by Thundaga or Spell Fencing, in order to eliminate him quickly. Otherwise a Vampire with genomes such as Blizzard Blast, Hellfire or Deep Freeze can ignore Heinkel's protection and damage Crowe significantly.
When fought with Bahamut, the dragon can be easily dispatched with Doom, otherwise a Vampire with Water-based genomes can inflict massive damage on Bahamut. Abate Fire works greatly for this battle.
Ominas: "What is with you people!? Stay away from me! It's just not right! The cheek of it! Do you people d-despise me that much!? I-It was all your fault, anyways! Yeah, that's it! You're the ones to blame!"