Instantaneous duration spells.

Are they spells whose effect starts and ends right away?

Spells that remain forever?

Spells that remain until a creature saves?

All of the above and more? Yeah, it’s pretty all over the place and I get them confused a lot. 😕 The magic of an instantaneous duration spell happens, and then is gone immediately. The magic is there and gone in an instant, but effects of that magic might remain, such as damage from a fireball, or healing from cure wounds.

— Dan Dillon 👥 (@Dan_Dillon_1) January 23, 2020