[RPG] Can one wizard prepare a spell that a second wizard wrote in the first wizard’s spellbook

dnd-5eequipmentspellcastingwizard

The rules for a wizard are that they can prepare spells that are in their spellbook, and cast ritual spells from their spellbook without preparing them. There is also the cost and time spent to copy a spell into your own spellbook.

But can one wizard add a spell into another wizard's spellbook?

In theory, it fulfils the rule of being in the book owning wizard's spellbook, but it doesn't fulfil the flavour of the wizard having to decipher and practice the spell for themselves.

Best Answer

Following the rules as they are written, this doesn't work because Wizards have unique notation systems

To quote the Wizard class (PHB page 115):

[...] Copying that spell into your spellbook involves reproducing the basic form of the spell, then deciphering the unique system of notation used by the wizard who wrote it. You must practice the spell until you understand the sounds or gestures required, then transcribe it into your spellbook using your own notation. [...]

Because of this even if another Wizard wrote a spell into your spellbook, it would be written in their notation and thus you could not actually use it. This is because:

[...] Preparing a new list of wizard spells requires time spent studying your spellbook and memorizing the incantations and gestures you must make to cast the spell [...]

You cannot memorize the incantations and gestures of a writing system you can't read, so you cannot prepare a spell written into your spellbook by another Wizard.


A GM can rule however they think best fits the narrative

Of course, this all only works under some very strict readings of the rules. A GM is certainly allowed to rule otherwise, especially if the narrative of the story makes sense here. If Wizard A knows the notation system Wizard B uses and writes a spell into B's spellbook (which would still have the time and gp costs), I see no reason B couldn't prepare those spells. After all, to an outsider, the spells written by A and the spells written by B are completely indistinguishable.