Slithrin, Eater of Land

Companion —Your starting deck contains no
Plains, Islands, Swamps, Mountains or Forests.
Whenever a nonbasic land enters the battlefield
under your control, you may sacrifice a land. If
you do, draw a card and add {w},{u},{b},{r} or
{g} to your mana pool. If you don't, Slithrin,
Eater of Land deals 3 damage to up to one target
creature an opponent controls and 3 damage to
you.