Here's the entrance to the Miner's Sanctuary, a field made of precious crystals. Its card info says:
Miner's Sanctuary
Field Spell
Once per turn, depending on the number of "My Crystallized Pony" monster you control, activate 1 of these effects: - 1: Inflict 500 damage to your opponent. - 2: Your opponent discards 1 random card. -3: Destroy 1 monster your opponent controls. - 4: Draw 1 card. - 5: Discard 1 card. Send all monsters your opponent controls to the Graveyard. You cannot conduct your Battle Phase this turn. - 6+: Destroy all Spell and Trap Cards your opponent controls.
Rare