Kaya, Orzhov Usurper
Legendary Planeswalker — Kaya
+1: Exile up to two target cards from a single graveyard. You gain 2 life if at least one creature card was exiled this way.
−1: Exile target nonland permanent with mana value 1 or less.
−5: Kaya deals damage to target player equal to the number of cards that player owns in exile and you gain that much life.
3
Illustrated by
Ravnica Remastered#194RareEnglishLegality
Rulings
Jan 25, 2019
If a permanent has 
in its mana cost, X is considered to be 0.
Jan 25, 2019
Tokens that aren’t a copy of something else don’t have a mana cost. Anything without a mana cost normally has a converted mana cost of 0.
Jan 25, 2019
Kaya’s last ability causes you to gain life equal to the number of cards the target player owns in exile, even if an effect causes her to deal more or less than that amount of damage to that player.