Can the Medallions reduce additional costs listed in card text, like doing damage with Drain Life or splitting up a Fireball?
The Diamonds don’t specify that they reduce casting cost, so can “pay for” additional costs. Q: So Ertai’s Meddling doesn’t actually say that the spell doesn’t resolve at the usual time… A: Oops. As “well duh” errata, Ertai’s Meddlng has the spell resolve once the last counter has gone away instead of at the usual time.