Cards exiled as resources for Alberix are exiled face up.

If two or more permanents have the world supertype, all of them are put into their owners’ graveyards except the one that has had the world supertype for the shortest amount of time. If there’s a tie for the shortest amount of time, all world permanents are put into graveyards.

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!).

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.

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.