Smashing a creature into surface over distance?

Because falls are instant, w/ my newly gained 50ft flight I was thinking about:

1) Grapple attack creature under my weight limit

2) Fly them some distance into high ceiling for damage

3) Drop them for free for instant non Action fall damage

What damage might the ceiling smash do? cheers

None RAW. There are no general rules for "smashing things into other things" that aren't "your weapon" into "your target". Any damage you would impose would be homebrew.

laffingist, if it helps you somehow:

- warlock repelling blast into a wall
- Involuntary movement and obstacles
- Pushing an enemy against a wall or another opponent

I might consider "smack them into the ceiling" to be an unarmed strike, but D&D doesn't have any rules about momentum, so that's it.

Anyway, smashing them into the ceiling at speed without smashing yourself would be impossible if there were -- there'd be no way to brake suddenly just after they hit.

Moving a Grappled creature up against a wall or ceiling deals no damage per se, but if one wanted accomplish such as an improvised action the DM could tell whether its possible and what kind of D20 Test you need to make, if any. Another option could be to take the Attack action and make an  Unarmed Strike to reflect such forceful blow for example or use other improvised damage.