Garg, The Mind Goblin

When Garg, The Mind Goblin enters the battlefield, all other creatures get -0/-2 until
end of turn.
Then, whenever a creature dies this turn
Garg, The Mind Goblin gets a cummies counter.
Instants and sorceries you control cost {1} less
to cast for each cummies counter on
Garg, The Mind Goblin.
"Yargle I've come to gargle"
-Garg, The Mind Goblin