Rin and Seri, Inseparable (Buy-A-Box) [Core Set 2021] Zendikar Tokens then you can attach this

then you can attach this card to it as material

Set: Battle Pack Tournament Prize Cards Card type: Fusion/Effect Monster Rarity: Starfoil Rare Attack: 2400 Defense: 1500 "Gladiator Beast Bestiari" + 1 "Gladiator Beast" monster Must first be Special Summoned (from your Extra Deck) by shuffling the above cards you control into the Deck

If this card is Link Summoned using DARK

Set: Commander Anthology Volume II Type: Land Rarity: Uncommon {T}: Add {C}

Set: Mystery Booster Type: Enchantment Rarity: Uncommon Cost: {U} {3}{U}{U}: Shuffle your library

Rin and Seri, Inseparable (Buy-A-Box) [Core Set 2021] Zendikar Tokens then you can attach thisSet: Core Set 2021 Type: Legendary Creature Dog Cat Rarity: Mythic Cost: {1}{R}{G}{W} Whenever you cast a Dog spell, create a 1 1 green Cat creature token. Whenever you cast a Cat spell, create a 1 1 white Dog creature token. {R}{G}{W}, {T}: Rin and Seri, Inseparable deals damage to any target equal to the number of Dogs you control. You gain life equal to the number of Cats you control.