Ask Wizards is a weekly feature that allows you to ask us questions! If you'd like to submit your question please email it to AskWizards@wizards.com. We aren't able to answer every question we receive, but if your question is good, it might show up in the coming weeks!
Q: How do phenomena affect the deckbuilding rules for a planar deck?
A: From Matt Tabak, Rules Manager for Magic
In phenomenal ways!
Okay, there’s a little more to it than that.
Each planar deck must have at least ten cards (including planes and phenomena) and no more than two of them can be phenomenon cards.
If you’re using the single planar deck option, that deck must be at least forty cards or at least ten times the number of players in the game, whichever is smaller. The maximum number of phenomenon cards in the single player deck is then twice the number of players in the game.
Each card in a planar deck must have a different English name.
Q: Planeswalkers can be used once per turn cycle. Magic already had a mechanic for visually representing this restriction (tapping). Why don't they use it?
A: From Mark Rosewater, Head Designer for Magic
Because there are ways of untapping permanents and we didn't want players getting around the once per turn limitation.
This question was originally answered on Mark Rosewater's Tumblr.