E.R.A.S.E.R.

The E.R.A.S.E.R, or Evil Reddish Airship Sent on an Epic Rampage, is the boss of the Flipbook mission. It moves at half the speed of a Lead Bloon, takes 949.39 hits to destroy (rounded to the nearest one, making it 949 hits, and has an ability:

Erase Erases a tower, (4th and 5th tier upgraded towers and all agents are unaffected, so are things in Eva Suits getting rid of it completely!

It holds 3 P.E.N.C.I.L.s when popped.