Amsera, Time-Sculptor

Eminence — As long as Amsera, Time-Sculptor
is in the command zone or on the battlefield,
spells you cast on extra turns cost {1} less to cast
for each time you've cast your commander this
game.
Prowess
At the beginning of each opponent's upkeep, you
may pay {u}{r}{w}. If you do, that player takes an
extra turn after this one.