@JeremyECrawford Can sorcerers replace their known cantrips for other sorcerer cantrips when they level up, or can they only do that with known sorcerer spells of first level or higher?
— adamTwright (@adamTwright) March 16, 2018
The sorcerer's Spellcasting trait lets you replace a sorcerer spell you know when you reach a new level in the class. The spell must be of a level for which you have spell slots, which means it can't be a cantrip; cantrips don't use spell slots. #DnD https://t.co/JOOJhsc5qA
— Jeremy Crawford (@JeremyECrawford) March 16, 2018
“SPELL LEVEL
Every spell has a level from 0 t o 9 . A spell’s level is a general indicator of how powerful it is, with the lowly (but still impressive) magic missile at 1st level and the earth-shaking wish at 9th. Cantrips-simple but powerful spells that characters can cast almost by rote are level 0. The higher a spell’s level, the higher level a spellcaster must be to use that spell.
Spell level and character level don’t correspond directly. Typically, a character has to be at least 1 7th level, not 9th level, to cast a 9th-level spell.”
“Additionally, when you gain a level in this class, you can choose one of the [Spell Caster] spells you know and replace it with another spell from the [Spell Caster] spell list, which also must be of a level for which you have spell slots.”
For what it’s worth, I’d interpret the last clause to be about stopping Players from taking spells from levels they’re not yet able to cast : You just know some people would if they could.
I don’t think it’s about preventing Cantrips from being swapped. Cantrips don’t have ‘Slots’ b\c they have no “Upper Limit” on the number of times they can be cast in a day … except for the 14,400 6-second Turns in 24 hrs. (Maybe Cantrips have 14,400 ‘Slots’.)
If they had intended to prevent 0-th lvl spells from being swapped, why wouldn’t they have explicitly said so ??