A 20 does not mean the spell achieves something out of its capabilities, what is this five year olds playing DnD?
D&D is ultimately a set of rules to guide a group improv storytelling session. One of the first rules of improv is “yes and” so you go with it within the confines of the game rules as well as what people are comfortable with. This is where /u/starbuck@lemmy.world’s suggestion of “Ranlar slowly rises from his wheelchair before collapsing under his own weight as his atrophied legs give out. Your party must now find a way to move him away from the orcs without using his newly healed legs, perhaps on a nearby chair with wheels.” Fits so well. It "yes and"s the spell while remaining true to the other player’s wishes.
The DMs job is to maintain the fun for the players, and if one player is ruining others fun they need to be spoken with and kicked out if they aren’t able to be a team player. Personally, I treat a NAT20 (and critical failures) as an opportunity to do something comical that helps advance the story and improve the lore, because that creates the moments you tell to others when sharing fun stories about D&D
Honestly, as a DM, when this doesn’t infringe on other player’s fun like here I don’t mind doing extraordinary stuff for the Nat 20
I have had players make persuasion checks against me before when they want to do something that’s explicitly outside the rules but I think it would be cool. Depending on how cool I think it would be, the DC can be anywhere from 10 to 20, and the player doesn’t have proficiency
Taking away someone’s intentional, roleplayed disability definitely falls under “infringing on someone’s fun”, though. If the player (not just the character) is also disabled and trying to represent themselves in the game, this goes beyond infringing on fun straight into lowkey offensive. I would never let this nat 20 work. Maybe it fixes the wheelchair or something.
Main issue is the wheelchair itself. No adventurer would ever use a wheelchair, the only reason we can use wheelchairs now are uniform roads and ada mandated ramps. Magic carpets exist and are cheap in game and don’t make you a liability.
What gave you that idea? Games make other players do stuff they don’t want all the time.
