But the predictability combined with the 2 damage to your creatures just makes it ineffective and weak overall
The 1/1 Red Devil that deals a damage when it dies is a unique token, but can be produced by an Uncommon and neither of the cards that make it (Dance with the Devil and Devil's Playground) seem very playable
Its even flexible: Demonic Consultation and Tainted Pact can be tutors, and Thassa's Oracle works with about a thousand other combos
Thats when Megatron transforms into Megatron, Tyrant, a massive 7/5 that prevents opponents from casting any spells during combat, removing their ability to play combat tricks
Constructed merfolk decks, especially in Modern, leverage Aether Vial as a way to slip creatures into play under counterspells, and without paying for them
You can also drop it later in the game to refill your hand