Elliseyence, Well Overflowing

{x}: Remove all storage counters from Elliseyence,
then add X storage counters to Elliseyence.
Remove X storage counters from Elliseyence:
Add X mana. Use this mana only to cast spells
and activate abilities with {x} in their cost, and
only to pay for {x}. If X is ten or more, spells
cast this way gain flash, abilities activated this
way can be activated as instants, and any one
instance of damage dealt by them is doubled.