Clavicus, the Chronomancer

You may pay {u}{u} instead of the given mana cost
of the first Instant or Sorcery spell you cast on your
turn.

Overload {6}{u}{u} (You may cast this spell
for its overload cost. If you do, change its text
by replacing all instances of "the first" with
"each".)

"The most powerful of all magics..."
- Arthur Aguefort