Pencil of the person who wrote this world. Can rewrite the world too. Just make sure not to break the ti- oops.

1/day, you can cast the wish spell, replacing the verbal component with the somatic component of writing in the air with the pencil. If you use the spell for an effect other that replicating a spell, the pencil tip has a 50% chance of breaking. If the pencil tip breaks, the pencil cant cast the wish spell for 7 days, after which the tip regrows. Otherwise, the wish spell gives you no adverse effects.

Additionally, 3/day, you can erase the effect of a spell being cast with a reaction. Erasing a 9th level spell takes 2 uses of this effect.