Brain Collector

Ingest Brain. The brain collector can carefully remove the brain from a dead or incapacitated creature using surgical tools and techniques.  This procedure requires 1 hour of uninterrupted work to complete.  The removed brain is then swallowed by the brain collector and moves to a specialized compartment in the creature's head.  The brain collector can consume up to 12 brains at one time.  It can expel a brain if it chooses, as an action.

The brain collector gains 1 spell for each brain it collects, beginning with a 1st-level spell for the first brain, a 2nd-level spell for a second brain, and a 3rd-level spell for a third brain.  This process repeats, starting with a 1st-level spell for the fourth brain, followed by a 2nd-level spell for the fifth brain and so on.  A brain collector possessing a full collection of 12 brains gains four 1st-level spells, four 2nd-level spells and four 3rd-level spells.  It also gains one cantrip for every three brains consumed.  The brain collector gains a random spell of the appropriate spell level from the wizard's spell list each time it consumes a brain.  These spells are cast innately (see below); cantrips can be cast at will and leveled spells can be cast once per day.

Innate Spellcasting.  The brain collector's innate spellcasting ability is Intelligence (spell save DC 17, +9 to hit with spell attacks).  It can innately cast spells, requiring no components, as determined by the number of brains it currently has swollowed using its Ingest Brain trait.

Bite. Melee Weapon Attack: +8 to hit, reach 10 ft., one target. Hit: 16 (2d10 + 5) piercing damage.