Bangle of the Arcane Assassin (Patreon)

Wondrous item, rare (requires attunement by a spellcaster)

Once per turn while wearing this bangle, you can deal an extra 3d6 damage to one creature you hit with a spell attack if you have advantage on the attack roll. The damage is of a type dealt by the spell attack. If you're a rogue, you can choose for the amount of extra damage you deal to be equal to your Sneak Attack damage instead; you can still only deal Sneak Attack damage once per turn. If a spell would allow you to attack multiple times over the course of its duration, this extra damage can only be dealt on the turn the spell is cast.

In addition, you can ignore the verbal component required for any enchantment or illusion spell you cast while you're in total darkness and wearing the bangle.

Without so much as a tap, her sandaled feet landed on the marble floor. It was easier than she expected to get inside. Still, she wasn't pleased the group had forced her to wear black; she knew she could accomplish this task even in her usually red and gold garb.

A door creaked open down the hall. Without thinking, she pressed herself against the wall, crept behind him and silently incapacitated him with an electrified hand to his shoulder. He was nearly twice her size, but she was still able to drag him back into the room, her dark bangle still crackling with the remaining arcane energy. She closed the door, looked around, and realized this was the bedroom she was looking for. Convenient.

"Saiya, it's been ten minutes. You've only got five more before the guards rotate. How's it going?" She heard the deep voice clearly in her head and giggled to herself. Khash always worried too much.

"I'll be out in just a moment. I just need to take a quick peek through his drawers for anything shiny."