Rin and Seri, Inseparable (Borderless) [Secret Lair Drop Series] restock {T}: Create a 1/1 colorless

{T}: Create a 1/1 colorless Sliver creature token

What do you think players are describing with these clues

The banner itself displays the embossed iconography of the Dark Angel Chapter banner and is decorated with tassels

each associated with a colored portal

well fitting

Rin and Seri, Inseparable (Borderless) [Secret Lair Drop Series] restock {T}: Create a 1/1 colorlessSet: Secret Lair Drop Series 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.