D&Dtools1

You feel slightly dizzy as the power of your spell rewrites the knowledge within your mind.
Rary's arcane conversion allows you to exchange a prepared wizard spell for another spell of equal or lower level.
For instance, upon casting this spell, you could choose to lose a prepared fly spell and have fireball prepared in its place.
The replacement spell must be one already scribed in your spellbook.
The new spell is now prepared and ready to cast as normal, just as though you had prepared it when you last studied your spells.