Merchants Guildhall

{t}{u}
When Merchants Guildhall enters play, all Drow Rogues Explore. (Whenever a creature you control explores, reveal the top card of your library. If the revealed card is a land, put that card into your hand. If its not a land card, put a +1/+1 counter on the exploring creature. Then decide whether the nonland card goes back on top of your library or into your graveyard.)
At the beginning of combat you may pay {2},
Tap any Drow Rogue creature, they Explore.