Wilrick's Pointed Hat

Wondrous item (head), uncommon (requires attunement by a spellcaster)

This conical hat of deep purple velvet is decorated with platinum threads along its wide brim, and it ends in a platinum tassel. This hat once belonged to Wilrick Whitegaze, a member of the Obsidian Synod.

Wearing the hat magically enhances all your senses except for your sight, which becomes blurred. You gain a bonus to your Perception and Investigation checks equal to your spellcasting modifier, but you have disadvantage on all vision-based Perception checks.

While you wear the hat, you can also cast Detect Magic at will, and you have advantage on Perception checks if what you are trying to perceive is detected by that spell.

Garb of the Synod

If you have several items that belonged to members of the Obsidian Synod, you can attune to all of them using a single attunement slot. You gain benefits depending on how many items you have equipped:

1 item: The Gift of Alacrity and Magnify Gravity spells are added to your spell list.
2 items: The Pulse Wave and Gravity Sinkhole spells are added to your spell list, and you can cast Disguise Self at will. You can use the spell to perfectly take on the appearance of any Synod member whose item you are attuned to.
3 items: The Temporal Shunt and Gravity Fissure spells are added to your spell list, and when you use your final spell slot of sixth level or lower, roll a d6. If the number rolled is the same as the level of the spell slot you spent, you regain one slot of that level.
4 items: The Dark Star and Reality Break spells are added to your spell list, and you gain a +1 bonus to spell attack rolls, and your spell save DC increases by 1.