Ancalagon
Dusty Dragon
Why?
Because the new monster format has monsters not actually casting spells
Because the new monster format has monsters not actually casting spells
Dungeons & Dragons Just Nerfed One of Its Most Popular Spells
A recent design change in Dungeons & Dragons had some unexpected consequences on a popular spell. [...]
comicbook.com
Going back to the example in the first paragraph, a Level 5 PC could easily shut down that evil sorcerer trying to fireball his party, provided that the sorcerer was within range and the PC was ready to burn a 3rd level spell slot. However, they wouldn't be able to stop a "Fiery Explosion" action, as the description for that action does not describe it as a spell.