Blue jelly

j blue jelly
Difficulty	5
Attacks	Passive 0d6 cold

j blue jelly
Difficulty	5
Attacks	Passive 0d6 cold
Base level	4
Base experience	45
Speed	0
Base AC	8
Base MR	10
Alignment	0 (neutral)
Frequency (by normal means)	2 (Quite rare)
Genocidable	Yes
Weight	50
Nutritional value	20
Size	Medium
Resistances	Cold, poison
Resistances conveyed	Cold (13%), poison (13%)
A blue jelly: can flow under doors. does not need to breathe. cannot pick up items. has no eyes. has no limbs. has no head. is mindless. does not eat. (*) is neither male nor female. is normally generated hostile.
Reference	monst.c#line503

A blue jelly, j, is a type of monster that appears in NetHack. Like most jellies, it is eyeless, amorphous, and sessile.

A blue jelly has a passive attack that triggers if attacked in melee, dealing cold damage against attackers without cold resistance dependent on their level while increasing the jelly's HP by half the damage inflicted - if enough HP is gained from this, the jelly will undergo division, halving its HP (rounded up) and creating a second jelly with almost the same amount of HP. Blue jellies possess poison resistance and cold resistance.

Eating a blue jelly corpse or tin has roughly a ²⁄₁₅ chance each (13%) of conferring cold resistance or poison resistance.

Generation

Randomly generated blue jellies are always created hostile.

Blue jellies appear among the j that make up the second quest monster class for Knights, and makes up ⁶⁄₁₇₅ of the monsters that are randomly generated on the Knight quest.

Strategy

Avoid attacking a blue jelly in melee unless you have cold resistance: blue jellies are much tougher than might be expected, and their cold passive attack can be deadly to inexperienced players. At their base level, they do (4+1)d6 damage, which gives a range of 5–30, and they can be generated at much higher levels. Ranged attacks are preferable, but make sure you have enough charges or projectiles options to finish the job—projectiles in particular will not be retrievable until the jelly is dead.

A lance or polearm can pound away safely at a distance and take a blue jelly out easily, and sources of fire damage can also make short work of them. The aklys is a solid option for throwable weapons that should likely be prioritized below pounding, but above other thrown weapons: at worst, the aklys has a ¹⁄₁₀₀ chance of failing to return, but will most likely deal enough damage for a hero to finish it with any remaining projectiles, preserving valuable darts, wand charges and/or other items.

Blue jellies are frequently employed for boulder forts, stashes and the like, since they are completely immobile and their damage is easier to resist.

History

The blue jelly first appears in NetHack 3.0.0.

In NetHack 3.4.3 and earlier versions, including some variants based on those versions, blue jellies can be instrumental in farming the Rider Death.

Variants

UnNetHack

In UnNetHack, a blue jelly appears in the northeastern-most room of Asmodeus' Lair.

SpliceHack

In SpliceHack, a blue jelly appears in the northeastern-most room of Asmodeus' Lair as in UnNetHack.

EvilHack

In EvilHack, blue jellies are vulnerable to fire. This also applies to Hack'EM.

Encyclopedia entry

I'd planned how to prevent the lock from sealing behind me; it required a temporary sacrifice, not cleverness. I used the door itself to help me cut off a portion of my body, after shunting all memory from the piece to be abandoned. The piece, looking inexpressibly dear and forlorn for a bit of blue jelly, would force open the outer door until I returned and rejoined it.

[ Beholder's Eye, by Julie E. Czerneda ]

dNetHack, notdNetHack and notnotdNetHack

The tissue injury resulting from frostbite is produced in two ways. The most obvious is actual freezing of the tissues. Although ice crystals form between the cells and grow by extracting water from them, the cells are physically disrupted by the ice crystals only to a limited extent. The dehydration and osmotic and chemical imbalances resulting from extraction of water from within the cell injure them, but permanent damage may be small. (...) The second mechanism of tissue injury by frostbite, which is much more significant is loss of blood supply to the tissues. Blood may flow through larger vessels but (one of the signs of adequate rewarming is a flushing of the frozen area) oxygen cannot be deliver to the tissues because the small blood vessels that would carry it have been lost.

[ Hypothermia, Frostbite, and Other Cold Injuries: Prevention, Survival, Rescue and Treatment by Gordon G. Giesbrecht, James A. Wilkerson ]