Sacrifice (Retro) [30th Anniversary Edition] Event and it's returned from the

and it's returned from the battlefield to its owner's hand at the beginning of the next end step

where X is the number of Soldiers you control

"These skittering creatures were created to hunt the one true threat to Phyrexia: dissent

you'll find:

Set: The Brothers' War Retro Artifacts Type: Artifact — Equipment Rarity: Rare Cost: {2} Equipped creature has first strike and gets +X/+0

Sacrifice (Retro) [30th Anniversary Edition] Event and it's returned from theSet: 30th Anniversary Edition Type: Instant Rarity: Uncommon Cost: {B} As an additional cost to cast this spell, sacrifice a creature. Add an amount of {B} equal to the sacrificed creature's mana value.