Rile Up the Warrens

Whenever one or more Goblins you control deals combat damage to a player, you may pay {x},
where {x} is less than or equal to the number of Goblins that dealt combat damage to a player
this turn.
If you do, reveal the top {x} cards of your library.
You may put a Goblin card with converted mana
cost {x} or less into play. Then put all remaining
cards on the bottom of your library in a random
order.