Crystalline Eminence

At the beginning of each opponent's upkeep,
if the Crystal of Truth is on the battlefield,
they may pay {x}. If they do, create that many
treasure tokens and they gain twice that
much life.
If you control 10 or more treasure tokens, create
a Great Dim Emblem with "Vanishing 10. At
the beginning of your upkeep, conjure a card
from Thurma's spellbook into your hand."