Rin and Seri, Inseparabler — ruling 1

Replacement effects that modify creatures of a certain type as they enter will apply after you apply Rin and Seri, Inseparabler’s first and second abilities, as appropriate. For example, if you control Rin and Seri, Inseparabler as well as a permanent with “Each Dog you control enters with an additional +1/+1 counter on it” and you create a 1/1 Cat token, that Cat token will be a Dog Cat token and will enter with a +1/+1 counter on it, a woof, and a purr.

Rin and Seri, Inseparabler — ruling 2

Playtest cards aren’t legal for play in any tournament format other than Mystery Booster Limited formats. On the other hand, we expect they will spice up a wide variety of non-tournament games (as long as everyone’s on the same page about using them!).

Rin and Seri, Inseparabler — ruling 3

Playtest cards use a modified version of game symbols, such as {T} and {W}. These modified symbols should be treated as the standard symbols during play.

Rin and Seri, Inseparabler — ruling 4

For many playtest cards, you’ll need to make a generous assumption that basic game rules would be updated to allow them to work. The Mystery Booster 2 Playtest Card Notes section (reproduced here in individual Gatherer rulings) provides guidance for fitting these cards into the existing rules structure.

Rin and Seri, Inseparabler : règles, fonctionnement et interactions (MTG)

Rin and Seri, Inseparabler is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

All Cats you control are Dogs in addition to their other types. All Dogs you control are Cats in addition to their other types. Cats and Dogs you control have haste.

How it works : Rin and Seri, Inseparabler

Original English text — Wizards of the Coast / Scryfall

#1November 8, 2024· Wizards of the Coast
Replacement effects that modify creatures of a certain type as they enter will apply after you apply Rin and Seri, Inseparabler’s first and second abilities, as appropriate. For example, if you control Rin and Seri, Inseparabler as well as a permanent with “Each Dog you control enters with an additional +1/+1 counter on it” and you create a 1/1 Cat token, that Cat token will be a Dog Cat token and will enter with a +1/+1 counter on it, a woof, and a purr.
No other card is named in this ruling.
#2November 8, 2024· Wizards of the Coast
Playtest cards aren’t legal for play in any tournament format other than Mystery Booster Limited formats. On the other hand, we expect they will spice up a wide variety of non-tournament games (as long as everyone’s on the same page about using them!).
No other card is named in this ruling.
#3November 8, 2024· Wizards of the Coast
Playtest cards use a modified version of game symbols, such as and . These modified symbols should be treated as the standard symbols during play.
No other card is named in this ruling.
#4November 8, 2024· Wizards of the Coast
For many playtest cards, you’ll need to make a generous assumption that basic game rules would be updated to allow them to work. The Mystery Booster 2 Playtest Card Notes section (reproduced here in individual Gatherer rulings) provides guidance for fitting these cards into the existing rules structure.
No other card is named in this ruling.