Yes, you can still potentially cheat the unlock cost and get your effect: so long as your cheating ability says cast without paying its mana cost or something similar
Myutant Cry English - Near Mint - 1st Edition Product Details Number : PHRA-EN000 Rarity : Common Attribute : TRAP Card Type : Normal Trap Description : During the Main Phase: Fusion Summon 1 "Myutant" Fusion Monster from your Extra Deck, by shuffling the Fusion Materials listed on it into the Deck, from among your cards on the field, in your GY, and/or your face-up banished cards
In this case, the Quarter Century products released last year may be a better alternative to obtain high rarity cards that can also be played with
The theme is more elemental and less spooky, but still clever and competitive
Rakdos, the Muscle Theft decks built on Threaten effects often employ sacrifice outlets to steal an opponent's creature, attack with it, and then get rid of it before control changes again