This tattoo depicts an eldritch tentacle wrapped around a brain. When in the presence of Aberrations it heats up. The higher the Aberration's CR, the hotter it gets.

Pain of the Far Realm. When the creature attuned to this tattoo feels pain, the tentacle squirms and reels.

Tattoo Attunement. To attune to this item, you hold the needle to your skin where you want the tattoo to appear, pressing the needle there throughout the attunement process. When the attunement is complete, the needle turns into the ink that becomes the tattoo, which appears on the skin. If you have multiple magic tattoos, they count as a single magic item with regard to the number of magic items you can attune to. If your attunement to the tattoo ends, the tattoo vanishes, and the needle reappears in the closest unoccupied space to you.

Notes: To attune to this item, you hold the needle to your skin where you want the tattoo to appear, pressing the needle there throughout the attunement process. When the attunement is complete, the needle turns into the ink that becomes the tattoo, which appears on the skin. If you have multiple magic tattoos, they count as a single magic item with regard to the number of magic items you can attune to. If your attunement to the tattoo ends, the tattoo vanishes, and the needle reappears in the closest unoccupied space to you.