All deadly puddings are immune to acid, cold, and poison. Lightning bolts and blows from weapons divide them into smaller puddings, each able to attack exactly as the original pudding. Fire causes normal damage, as do magic missiles. Puddings can ooze through cracks that are at least 1 inch wide and can travel on ceilings and walls (falling on victims as a nasty surprise) at the same speed as on a level surface.

Puddings reproduce by fission. They are adapted to live in a wide variety of climates.
Puddings starting with 11-30% of maximum possible hit points are 3 feet to 4 feet in diameter; with 31-50% of full hit points, 5 feet wide; with 51-70% of full hit points, 6 feet wide; with 71-90% of full hit points, 7 feet wide; and with 91-100% of full hit points, 8 feet wide. If a pudding is split up so it becomes less than 3 feet wide, it becomes thinner but retains its 3-foot diameter. Because puddings do not use all of their mouth openings (which cover their exposed surfaces), the smallest pudding does the same damage as the largest.

Black pudding acid is highly corrosive, inflicting 3-24 points of damage per round to organic matter and dissolving a 2-inch thickness of wood equal to its diameter in one round. Black puddings also dissolve metal. Chain mail dissolves in one round, plate mail in two; each magical "plus" increases the time it takes to dissolve the metal by one round (thus plate mail +3 takes two rounds to dissolve for being plate mail, plus three rounds for having a +3 magical bonus, for a total of five rounds).