Black Cyst

Amorphous. The cyst can move through a space as narrow as 1 inch wide without squeezing.

Corrosive Form. A creature that touches the cyst or hits it with a melee attack while within 5 feet of it takes 4 (1d8) necrotic damage. Any nonmagical weapon made of metal or wood that hits the cyst corrodes. After dealing damage, the weapon takes a permanent and cumulative −1 penalty to damage rolls. If its penalty drops to −5, the weapon is destroyed.

Nonmagical ammunition made of metal or wood that hits the cyst is destroyed after dealing damage.

The cyst can eat through 2-inch-thick, nonmagical wood or metal in 1 round.

Natural Levitation. The cyst regularly appears as a gelatinous floating orb, hovering at least a foot above the ground. Effects that alter the ground or cause tremors have no effect on the cyst unless it is choosing to touch the environment, for example, if it is pushing itself through a narrow crack.

Pseudopod. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 6 (1d6 + 3) psychic damage plus 18 (4d8) necrotic damage. In addition, nonmagical armor worn by the target is partly dissolved and takes a permanent and cumulative −1 penalty to the AC it offers. The armor is destroyed if the penalty reduces its AC to 10.

Encapsulate. Melee Touch Attack: +5 to hit, reach 10 ft., one target. The cyst attempts to grapple and enfold itself around one creature of the same size as itself or smaller. A creature that is touched must make a DC13 Strength save, or be grappled. A grappled creature cannot breath and will take regular suffocation penalties as applicable. Each turn the creature starts grappled in this way, they must make a DC13 Wisdom check or take 1 Intelligence damage, recoverable after a long rest or immediately with greater restoration The creature can attempt to break the grapple at the end of each turn. The grapple is immediately broken if the cyst is "split". A creature with Intelligence damage may suffer the following penalties if their score drops too low:

• INT 4-5: The character now struggles to read and may have difficulty understanding certain words. They are limited to understand one language.
• INT 2-3: The character cannot read or speak, and only has basic understanding of what is being said based on body language or expression. Think "animal intelligence".
• Int 1: The character is only barely above brain dead. They are conscious and can carry out functions necessary for life. They are alert enough to flee from danger, but cannot attack.
• Int 0: The character is comatose for 24 hours, or until restored with greater restoration.

Split. When a cyst that is Medium or larger is subjected to lightning or slashing damage, it splits into two new cysts if it has at least 10 hit points. Each new cyst has hit points equal to half the original cyst's, rounded down. New cysts are one size smaller than the original cyst.