Merfolk Treasure-Caller

Whenever a creature you control attacks, it explores (Reveal the top card of your library. Put that card into your hand if it's a land. Otherwise, put a +1/+1 counter on this creature, then put the card back on top or into your graveyard.)
{t}: Create a colorless Gem artifact token.
Sacrifice a Gem: Add one mana of any color to your mana pool.