Grisbrake Riders

Grisbrake Rider enters the battlefield with a
+1/+1 counter on it for each Mercenary you
control.
{2}{b}{b}, {t}: Search your library for two
Mercenary cards with converted mana cost 2 or
less, put those cards onto the battlefield, then
shuffle.
"Footprints in the snow leave an easy trail to follow.
Should be a simple job, boys."