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

 Corrosive form. A creature that touches the slug or hits it with a melee attack while within 5 feet of it takes 4 (1d8) acid damage. Any nonmagical weapon made of metal or wood that hits the slug corrodes. After taking damage the weapon takes a permanent and cumulative -1 penalty to damage rolls. If a penalty drops to -5, the weapon is destroyed after dealing damage. The slug can eat through 2-inch-thick nonmagical wood or metal in 1 round.

Pseudopod. Melee weapon attack: +3 to hit, reach 5ft., one creature. Hit 7 (2d6 +1) acid damage.

Acid spew: ranged weapon attack: +6 to hit, reach 150/300., one target. Hit 6 (2d6) plus 5 (1d8 +1).