Its fickle form holds hints of a thousand former identities.

Ravnica Remastered

Aetherplasm

Whenever Aetherplasm blocks a creature, you may return Aetherplasm to its owner's hand. If you do, you may put a creature card from your hand onto the battlefield blocking that creature.

Whenever this creature blocks a creature, you may return this creature to its owner's hand. If you do, you may put a creature card from your hand onto the battlefield blocking that creature.

Guildpact

Whenever Ætherplasm blocks a creature, you may return Ætherplasm to its owner's hand. If you do, you may put a creature card from your hand into play blocking that creature.