Staff of the Ivory Claw
Source: Explorer's Guide to Wildemount
Staff, rare (requires attunement by a spellcaster)
This gray-and-cerulean staff is topped with a small dragon claw carved from ivory. While holding the staff, you gain a +1 bonus to spell attack rolls. Whenever you score a critical hit with a spell attack, the target takes an extra 3d6 radiant damage.