Text (DI+errata): 0/0. ; Graft 2. ; {U},{Tap}: Gain control of target creature with a +1/+1 counter on it for as long as ~this~ remains on the battlefield. [Oracle 2009/07/08]
It only tests that the target is a creature and has a +1/+1 counter when the ability is announced and resolved. After that, control remains even if it stops being a creature or having a counter. [Dissension FAQ 2006/04/13]
If this card leaves play before the ability resolves, then the ability does nothing. [Dissension FAQ 2006/04/13]
