Tristan Lowe, Dark Summoner

Whenever an Eidolon creature enters the battlefield under your control, each opponent
loses 1 life.
{1}{b}{b}, Sacrifice an Eidolon creature: Put X
+1/+1 counters on Tristan Lowe, where X is the
sacrificed creature's power.
As long as Tristan Lowe has five or more +1/+1 counters on it, it has menace.