Spell Thief

You gain the ability to magically steal the knowledge of how to cast a spell from another spellcaster.

Immediately after a creature casts a spell that targets you or includes you in its area of effect, you can take a Reaction to force the creature to make an Intelligence saving throw. The DC equals your spell save DC. On a failed save, you negate the spell's effect against you, and you steal the knowledge of the spell if it is at least level 1 and of a level you can cast (it doesn't need to be a Wizard spell). For the next 8 hours, you have the spell prepared. The creature can't cast it until the 8 hours have passed.

Once you steal a spell with this feature, you can't use this feature again until you finish a Long Rest.