Unmask [The List] Human Elf Druid creatures can't attack unless their

creatures can't attack unless their controller pays {X} for each attacking creature they control

but it fled to the sky

Fist of Krosa: Create an X/X green Wurm creature token

Set: Innistrad: Double Feature Type: Land Rarity: Common Delve (Each card you exile from your graveyard while casting this spell pays for {1}

It can't be regenrated

Unmask [The List] Human Elf Druid creatures can't attack unless theirSet: The List Type: Sorcery Rarity: Rare Cost: {3}{B} You may exile a black card from your hand rather than pay this spell's mana cost. Target player reveals their hand. You choose a nonland card from it. That player discards that card.