Inspired by this answer and subsequent comments, I am curious if a PC can opt to take only part of the benefits of a regenerate spell.
The regenerate spell description states:
The target's severed body members (fingers, legs, tails, and so on), if any, are restored after 2 minutes. If you have the severed part and hold it to the stump, the spell instantaneously causes the limb to knit to the stump.
However, using the example from the linked question, say a PC wanted their severed tail to regenerate, but not their self-mutilated horns - would the PC be able to partially reject the regenerate spell, thereby allowing their tail to regenerate and not their horns?