Arcanum Things

• WOTC Official Reminder Textofficial rules
  Equip — Equip [cost] ([cost]: Attach to target creature you control. Equip only as a sorcery.)

• WWizards of the Coast2024-11-08
  Official Ruling
  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!).
• WWizards of the Coast2024-11-08
  Official Ruling
  The exchange happens on resolution of Arcanum Things’s Equipment swap ability and is simultaneous.
• WWizards of the Coast2024-11-08
  Official Ruling
  As Equipment swap resolves, you may reveal an Equipment card from your hand. If you don’t reveal an Equipment card, or if the exchange can’t be completed (such as if Arcanum Things is no longer on the battlefield, you don’t own Arcanum Things, or the new Equipment can’t be attached to the creature Arcanum Things is attached to), nothing happens.
• WWizards of the Coast2024-11-08
  Official Ruling
  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.
• WWizards of the Coast2024-11-08
  Official Ruling
  Playtest cards use a modified version of game symbols, such as and . These modified symbols should be treated as the standard symbols during play.

Rulings via Scryfall