Coiling Serpent

Flash, lifelink
When Coiling Serpent enters the battlefield, you
may tap it. When you do, tap target creature you
don't control. As long as Coiling Serpent and
that creature both remain tapped this way, they
don't untap during their controllers' untap steps.
At the beginning of your upkeep, put a +1/+1
counter on Coiling Serpent. Then, it deals
damage equal to its power to that creature.