Elder Deep-Fiend is a rare Creature — Eldrazi Octopus card from The List (PLST), collector number EMN-5. Current market price: $0.37, TCGplayer market prices via Scryfall.
Flash Emerge {5}{U}{U} (You may cast this spell by sacrificing a creature and paying the emerge cost reduced by that creature's mana value.) When you cast this spell, tap up to four target permanents.