Wrenn and One is played as a land. It doesn’t use the stack, it’s not a spell, it can’t be responded to, it has no mana cost, and it counts as your land play for the turn.

Due to its color indicator (appearing to the left of its type line), Wrenn and One is green. Color indicators apply in all zones, not just the battlefield.

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.

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

Wrenn is a planeswalker type, not a land type.

If Wrenn and One is changed into a basic land type, it continues to be a green Wrenn planeswalker, but it will lose its other abilities.

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!).

If Wrenn and One gains flash, or you have the ability to play Wrenn and One as though it had flash, you can ignore the normal timing rules for when during your turn you can play a land, but not any other restrictions. You can’t play Wrenn and One during another player’s turn, and you can’t play Wrenn and One if you don’t have any land plays remaining.