Casting Time: 1 Hour , Range: Touch , Components: V (Vocal) - S (Somatic) - M (Material) , Duration: 8 Hours
Special Material: rare mushrooms and algae worth a total of 500 gp, which the spell consumes
Effect
You adapt the physiology of a willing creature you touch to the dangers of the World Below, altering the creature so they can traverse the plane more safely. The spell reprograms nerves, grows a lining of lead in the skull, changes body chemistry, and more. It can also create up to three cosmetic changes determined by the caster, such as pointed ears, plaid skin, or sharp teeth. For the duration, the creature gains the following benefits:
The creature gains darkvision out to a range of 120 feet and tremorsense to a range of 60 feet.
The creature has advantage on Wisdom (Perception) and Dexterity (Stealth) checks.
The creature gains immunity to poison damage and the poisoned condition, and resistance to psychic damage.
The creature gains a climbing speed equal to its walking speed and can move up, down, and across vertical surfaces and upside down along ceilings, while leaving its hands free.
The creature can sweat acid. As an action, the creature can expend a Hit Die by rolling it, (and doesn’t add its Constitution modifier). The creature takes acid damage equal to the result, and any other creatures or nonmagical objects touching it take twice that amount of acid damage. The acid evaporates after this damage is dealt. This acid instantly destroys any web it touches, such as those created by the web spell. In addition, the acid corrodes any nonmagical armor worn by the creature, which takes a permanent and cumulative −1 penalty to the AC it offers. The armor is destroyed if the penalty reduces its AC to 10. However, the creature can produce this acid selectively on its body, i.e., only around its wrists and ankles. Another creature or object only takes acid damage if they are in contact with where the creature produces the acid.
At Higher Levels
Lore, some nice lore flavour and/or history