Greta, Ensemble Member

As Greta, Ensemble Member enters the battlefield, target creature you don't control is
under your control until Greta, Ensemble
Member leaves the battlefield. This creature is
tapped and cannot be untapped on your untap
step.
{b}: Sacrifice target creature, Greta, Ensemble
Member gains Indestructible and Trample until
end of turn.
{b}. {b}, {t}: Repeat Greta, Ensemble
Member's etb effect.