Trevenant & Dusknoir GX (SM217) (Jumbo Card) [Sun & Moon: Black Star Promos] Staff (2H)/Young you may play blue 'non-attack'

you may play blue 'non-attack' action cards from your arsenal as though they were an instant

Whenever Muxus attacks

Set: Multiverse Legends Type: Legendary Creature — Phyrexian Praetor Rarity: Mythic Cost: {5}{B}{B} Swampwalk (This creature can't be blocked as long as defending player controls a Swamp

000 Type: Legendary Artifact Creature — Necron Rarity: Rare Cost: {4}{B}{B} Deathtouch

When an opponent defeats this

Trevenant & Dusknoir GX (SM217) (Jumbo Card) [Sun & Moon: Black Star Promos] Staff (2H)/Young you may play blue 'non-attack'Set: Sun & Moon: Black Star Promos Type: Psychic Rarity: Promo Retreat cost: Colorless,Colorless,Colorless