Frostflame Surge

Spend only {s} on X.
Frostflame Surge deals damage equal to the
number of colors of {s} spent on X to each of X
targets. Tap each creature dealt damage this way.
They don't untap during their controllers' next
untap steps. Lands controlled by players dealt
damage this way don't untap during their controllers' next untap steps. ({s} is mana from
a snow source.)