Ancient City - Rainbow Ruins

You must have this many "Crystal Beast" cards in your Spell & Trap Card Zone to activate and to resolve these effects. ● 1+: This card cannot be destroyed by card effects. ● 2+: Once per turn (including the opponent's) you can halve the Battle Damage you take. ● 3+: During either player's turn, when a Spell/Trap Card is activated: You can send 1 "Crystal Beast" monster you control to the Graveyard; negate the activation, and if you do, destroy it. ● 4+: Once per turn, during your Main Phase: You can draw 1 card. ● 5: Once per turn, during your Main Phase: You can target 1 "Crystal Beast" card in your Spell & Trap Card Zone; Special Summon that target.

Field Spell Card spell