Siren's Call [Beta Edition] RC7 Choose your commander and overcome

Choose your commander and overcome both friend and foe in this definitive multiplayer Magic format

Set: EX: Delta Species Type: Water Rarity: Promo Retreat cost: 1

Set: Black & White: Emerging Powers Type: Item Rarity: Promo

and 3–8 Uncommon

Siren's Call [Beta Edition] RC7 Choose your commander and overcomeSet: Beta Edition Type: Instant Rarity: Uncommon Cost: {U} Cast this spell only during an opponent's turn, before attackers are declared. Creatures the active player controls attack this turn if able. At the beginning of the next end step, destroy all non Wall creatures that player controls that didn't attack this turn. Ignore this effect for each creature the player didn't control continuously since the beginning of the turn.