Ana, Benevolent Sniper

Reach, first strike
Whenever Ana, Benevolent Sniper enters the battlefield, tap target creature you don't control.
It doesn't untap during its controller's untap
step until target creature's controller is attacked.
{w}{b}: Each attacking creature gains a
-1/-1 counter until end of turn. Each defending creature gains a +1/+1 counter until end of turn.
"I wasn't cut out for retirement anyways."