The black pudding, P, is an amoeboid NetHack monster. Its most noteworthy characteristic is its ability to divide when hit by an iron item, leaving two black puddings (a process which also corrodes the weapon). It is the more powerful of the two monsters that can do this (the other being the brown pudding).
The black pudding is considered a fleshy monster, and is not vegetarian. This is presumably a pun on the fact that some types of blood sausage are known as "black pudding". (Also note the sausage-like tile used in the Windows version, presumably also playing on the same pun.)
Black puddings can be encountered early in the game due to sinks. It can be a good idea to kick sinks for this reason, as their low speed makes their powerful bite easily avoidable and their XP value can easily gain you an entire level.
On the other hand, kicking a sink can also summon a foocubus of opposite sex to the adventurer ("The dishwasher returns!"), and one of the possible negative seduction effects is a level drain ("You feel out of shape"). Level 1 adventurers should never kick sinks, as being drained from level 1 is an instadeath (unless you don't mind restarting). Those with a few more levels should weigh the risks.
When a pudding splits the current HP are divided equally between the two new puddings, so each split produces weaker ones until it dies attempting to split its last hitpoint. Thus, if things threaten to get out of hand, kill the newer ones first before they have time to regenerate.
If you have a pudding pet and a polymorph trap, you can split it, yielding more pets to polymorph. As the name is also cloned, you might want to rename them. See Abuse for ramifications of attacking and splitting your pet. When doing this, take care to use a Puddingbane, lest you kill your pet(s) and suffer the penalty.
Beginning in NetHack 3.6.0, black puddings leave globs instead of corpses when they are killed. Globs cannot be sacrificed, revived or tinned, making pudding farming a less useful tactic than in previous versions of NetHack.
Protect your armor
- Rustproof iron armor will not corrode.
- A corrodeproof bronze plate mail (the only copper armor) will not corrode.
- Body armor concealed under a cloak or robe will not corrode.
- You might let your uncursed or blessed +0 orcish helm corrode if you have a replacement available.
- You could step away from the pudding and remove your vulnerable armor; black puddings do not corrode what you do not wear.
A good strategy is to fight using ranged attacks, but many players will not have these armor problems; maybe you will not encounter a black pudding before you rustproof your armor.
Don't use iron weapons
Black puddings can corrode iron weapons. If you would wield an iron weapon and hit a black pudding, then the pudding might split and the weapon would corrode. (That is good if you want to block a wide path, but bad if the multiple puddings thoroughly corrode your armor.)
In earlier versions, killing black puddings left normal corpses (which could be eaten to provide useful intrinsics or sacrificed for a variety of gains) and death drops, leading to the infamous practice of pudding farming with a Puddingbane. However, Nethack 3.6.0 eliminated the ability of puddings to drop corpses, making this practice ineffective and pointless.
In SLASH'EM or Slash'EM Extended, black puddings never leave death drops, but they still drop normal corpses, and they also provide Poison (22%), Cold (22%) and Shock (22%) resistance. The practise of some Pudding farming is still interesting for sacrificing and for the intrinsics.