A great clarification by @JeremyECrawford here. Dunamancy is an umbrella “source” of magic, not an entirely new school of magic. The spells fit within existing schools, and the Dunamis-specific spell flavor text was toned down to help them fit into any setting beyond Wildemount! Dunamancy is a prominent narrative theme for this magic within my world, and can be carried into others. Outside of the subclasses that have access to them, it’s up to the DM to grant these spells as rewards, player goals, or just incorporate them overall!

— Matthew Mercer (@matthewmercer) January 30, 2020

And they are all amazing.

— Todd Kenreck (@ToddKenreck) January 30, 2020