The Battle Cats - Realm of Carnage (Deadly)
As long as you take out the first Bore with Whales fast enough, you can lure the R. Ost and try to take him out as fast as possible. Time your A. Bahamut well enough so that he can hit the R. Ost multiple times, while using ranged attackers as well. Not too bad, just make sure your timings at least make Bahamut not die immediately.