Drummer Doge is a stationary enemy that only appears in the Summer Diary event.
Has very slow attack speed, and negligible damage, but can stall your team for a long time with its long range and freeze ability. Still, unless you're a level 1 Cat, you really have nothing to fear. Awakened Bahamut can get the job done fast.
Time between attacks
300 000 HP
1800 (Area Attack)
Stop the movement of all Cat Units for 30f (100%)
It's probably a Balaluga enemy counterpart: Uber range, very low attack power and long time between attacks.
Drummer Doge appears to be beating a Taiko Drum, a traditional precussion instrument used in Japan.
Despite appearing to be carried by Doges, the Drummer Doge doesn't move.