Wand of Arcane Ventriloquism
This wand is small enough to be easily concealed. When you cast a spell, pick another spellcaster (either an ally or an enemy). Your spell emanates from their location as if they’d cast it, and anyone not familiar with arcane techniques will assume they were responsible for whatever spell you just threw. You can only pick a spellcaster who’s far away if your spell can reach that range normally.