Astra

Astra enters the battlefield with 4 star counters
{u}{x}: Remove a star counter, you take control
of target creature with converted mana cost {x}
{u}: Remove a star counter, tap target creature
{1}{u}: Remove a star counter, target creature
can't block until end of turn
{6}{u}: Remove a star counter, 3 target creatures
can't be blocked this turn