Theorycraft Grimoire

Wondrous item, legendary (requires attunement by a wizard)

This grimoire, bound in dark blue leather, feels slightly electric to the touch, and words and diagrams on its pages shift slightly. You can choose to use this grimoire as your spellbook and if you do so, you can alter your spells in two different ways when you cast them. The altered spells must be in the theorycraft grimoire for you to alter them.

Change Creature Type. If a spell targets a specific creature type, such as charm person targeting humanoids, you may alter the spell to target one of the following creature types instead: aberration, beast, fey, giant, or monstrosity.

Change Elemental Properties. If a spell deals acid, cold, fire, or lightning damage, you can choose for it to deal any other one of the given types of damage.