Matt, the Impetuous

At the beginning of each opponent's end step, if
that player didn't cast any instant or sorcery
spells, Matt, the Impetuous deals X damage to
that player, where X is the amount of mana
spent to cast Matt, the Impetuous.
Whenever you cast an instant or sorcery card, you
may pay {u}{r}. If you do, change its text by
replacing all instances of "target" with "each."
"Shocking, isn't it?"