Debt Burden

Enchant player
During enchanted player's upkeep they may
spend mana on Debt Burden. A total of X mana
over any number of their upkeeps must be spent
to destroy Debt Burden.
Cumulative debt: 20 %
(during enchanted player's end step increase
the remaining amount by 20 %, rounding up)
Enchanted player cannot win the game