yugioh stardust accelerator deck / Synchron from 𝓥𝓮𝓬𝓽𝓸𝓻 Yu-Gi-Oh! World Championship 2009 Stardust

Etali, Primal Storm becomes this Gruul abomination thanks to the power of Phyrexia

Basically, they sit outside the game (but not in a sideboard slot), get put into the Command Zone, and from there they generate effects

When resolving an opponent's card effect that targets an "Archfiend" monster you control, roll a six-sided die and negate that effect if you roll a 1, 3, or 6, and if you do, destroy that card

Cantrips become mana-neutral

Star Seraph Scale X LIGHT Level 4 [ FairyEffect ] ATK 1500 DEF 900 When this card is Special Summoned: You can Special Summon 1 "Star Seraph" monster from your hand, then you can place 1 LIGHT monster from your Graveyard on top of your Deck