R. Ost is among the most well-equipped pushers in the game. He has fast movement speed, high health, enough range to hide behind most peons, and a rapid Area Attack that will shred your cats. The icing on the cake is that he can do Critical Hits, which make fighting him much more inconsistent. Fortunately, he has five knockbacks to reduce his heavy pushing power.
Awakened Bahamut Cat can be used to chip off much of an R. Ost near the Cat Base, then let him be finished with the rest of your attackers. For this to work, Bahamut must be spawned while R. Ost is frozen or during R. Ost's backswing, and there can't be any other enemies in front of R. Ost.
Overall, this enemy is easy to counter on his own but can be a real pain when spawnedingroups or with enemies that take advantage of his many knockbacks such as Director Kurosawah.
Any unit exclusive to the Epicfest event will do very well against this avian atrocity. The Weaken effect helps a lot too, so don't be afraid to save an extra slot for Thaumaturge Cat.
A Metal enemy that only appears in the Golden Week and Silver Week events. It has the usual Metal ability of only taking 1 damage except for Critical Hits, but it has much lower stats all across the board and cannot perform Critical Hits itself.