Imira, Serpent of the Depths

Combine (When this creature comes into play, you may
combine it with another creature you control. The combined
creature has the names, creature types, added stats, added
converted mana cost, and abilities of both creatures.)
When another creature with Combine comes into play
under your control, make a copy of it. The copy loses
the Combine ability. Sacrifice it at the beginning of
your end step unless you pay {1}.