Master Chief, One man army

First strike, Trample
Each time you cast a artifact you may
{t}: roll a d20
1-10| Search your deck for an equipment spell.
11-19| Cast a artifact from your Graveyard.
20| Deal 5 damage to all your opponents creatures, Master Chief gains +0/+1 until the end of your
next turn for each creature destroyed this way.
You may only use this once every other turn.