Sub-Brain

Wondrous item, very rare (requires attunement)

This complex contraption is a marvelous mixture of science and the arcane. By implanting this small device behind the base of the skull, you are able to gain the benefits of having an additional brain.

• Installation. To have the sub-brain installed, you must have it surgically implanted. The procedure requires the surgeon to make six DC 15 Medicine checks over the course of an hour. Every failure increases the DC by 5. If the surgeon fails three times, the patient dies as their brain is destroyed.
• Extra Storage. Due to the increased memory capacity of the sub-brain, your Intelligence score increases by 2. This can increase your Intelligence above 20.
• Mental Fortitude. You gain advantage on all rolls to resist the effects of the charmed, frightened, and stunned conditions.
• Sensitive Circuits. The technology within this device is delicate in its complexity and can be damaged if hit just the right way. If you are damaged by a critical hit, roll 1d10. On a 1, the sub-brain is damaged and begins to malfunction. You instead receive -1d4 Intelligence and Wisdom as the sub-brain draws power from the primary brain to compensate for the damage. You must then undergo the installation process again to fix the sub-brain. This repair process only requires three successes to achieve.