The Barnacle

First Strike, Trample
When this creature enters the battlefield, it phases
out

Heart Attack! — When this creature attacks, put a blood clot counter on it. When this counter reaches 4, you lose half your life and exile this creature. {p/g}{p/g}Remove a counter.
Crashout — {x}{b}{b}{b}: Destroy {x}devided by 2 target permanents, if {x} is 20 or greater, you win the game