Siren's Call [Alpha Edition] Modern Masters 2015 these devices doubled the output

these devices doubled the output of Amrit Vatyam's forges

you may sacrifice an artifact

If you do and they guessed wrong

Only creatures can be enchanted this way

Activate only if Glory is in your graveyard

Siren's Call [Alpha Edition] Modern Masters 2015 these devices doubled the outputSet: Alpha 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.