# Medusa's Island

Medusa's Island

Location

Level 21–28 of theDungeons of Doom

Variants

First version
Second version
Third version
Fourth version

Bones

No

Mappable

Yes

Teleportable

No

Diggable floor

Yes

Diggable walls

varies

Medusa's Island is a special level that appears in NetHack, and is home to Medusa. The entire level is non-teleport, and is ineligible to leave bones files.

Contents

1 Generation

1.1 Common traits

2 First version
3 Second version
4 Third version
5 Fourth version
6 Strategy
7 Origin
8 History
9 Variants

9.1 UnNethack
9.2 SlashTHEM

10 References

Generation
The island is 1 to 4 levels above the Castle, placing it between dungeon levels 21 and 28. Monster creation on this level is biased towards chaotic monsters. 
There are four different versions of the island, each of which has an equal chance of being used.

Common traits
Each version of the level contains several statues representing Medusa's victims. Except as noted below, there will be:

Seven statues of random monsters scattered around the level. These statues will contain any equipment their monster type might usually be generated with, but will not have the usual chance of containing a random spellbook.
Five statues of player monsters with names and roles from the top-ten list in the same room as Medusa. These statues will be empty.
A historic statue of Perseus, containing (with independent probability):[1][2][3][4]
a 75% chance of a cursed +0 shield of reflection
a 25% chance of a +0 pair of levitation boots
a 50% chance of a blessed +2 scimitar
a 50% chance of a sack

The following information pertains to an upcoming version (3.7.0). If this version is now released, please verify that it is still accurate, then update the page to incorporate this information.

Any of the following maps may be mirrored and/or flipped.

First version

Medusa's Island (1)

Location

Level 21–28 of theDungeons of Doom

Bones

No

Mappable

Yes

Teleportable

No

Diggable floor

Yes

Diggable walls

No

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Medusa is waiting on the down stairs with the statue of Perseus. There is a random snake in each of the top and bottom corridors of her hall, two water trolls in the water to the right of the level, three giant eels and three jellyfish in the water to the left of the level, and ten other random monsters. In addition to the two marked squeaky boards, there are five other random traps on the level.

Second version

Medusa's Island (2)

Location

Level 21–28 of theDungeons of Doom

Bones

No

Mappable

Yes

Teleportable

No

Diggable floor

Yes

Diggable walls

Not on leftmost/rightmost islands

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Medusa is waiting on the down stairs with the statue of Perseus. There are a titan and a gremlin in the entrance hall, six electric eels and three jellyfish in the water to the left of the level, four stone golems and two cobras immediately outside Medusa's room, a random A and a yellow light in the back room of Medusa's hall, and thirteen more random monsters distributed fairly evenly across the level. In addition to the marked magic trap, there are four other random traps on the level.
In contrast to the other versions, the probabilities of the shield and boots in Perseus' statue are 25% and 75%, respectively. There is also an additional random monster statue, and all eight are placed to the left of Medusa's room as marked.
There are marked boulders in the entrance hall and on the right-hand island; the latter has a random wand beneath it. The walls of both the entrance hall and Medusa's hall are undiggable.
The wand is possibly a reference to NetHack 2.3e and earlier versions of NetHack. These versions did not have the Castle; instead, they placed the wand of wishing in one of the upper mazes, in a dead-end square with a boulder on top of it.

Third version

Medusa's Island (3)

Location

Level 21–28 of theDungeons of Doom

Bones

No

Mappable

Yes

Teleportable

No

Diggable floor

Yes

Diggable walls

some

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The up stairs are on the top-center island. The "stairs" marked above are the locations where the actual down stairs can be generated, with Medusa waiting on them; another will have the statue of Perseus, and the third will contain a fountain. Thirty hostile ravens populate the level, as well as two giant eels, two jellyfish, two wood nymphs, and two water nymphs. Two scrolls of blank paper are at the bottom of the southermost island as marked, as well as eight random items scattered around the level. Two rust traps, two squeaking boards, and one other trap are randomly placed. The rooms potentially containing Medusa have non-diggable walls, but the right half of the double room (excluding its left wall) is diggable, and trees may be chopped down. This level is "shortsighted", meaning monsters can only see you when you approach within a certain radius.

Fourth version

Medusa's Island (4)

Location

Level 21–28 of theDungeons of Doom

Bones

No

Mappable

Yes

Teleportable

No

Diggable floor

Yes

Diggable walls

No

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The up stairs are always on the islands to the right, with Medusa dwelling in her "palace" on the left.[5] The down "stairs" marked above are the locations where the actual down stairs can be generated, with Medusa waiting on that square - another will have the statue of Perseus in its place. The marked yellow dragon is generated asleep, and may have up to two babies sleeping by her. She also nests on one to three yellow dragon eggs, which may hatch into awake and hostile babies by the time you reach them. Also inhabiting the level are various, mostly slithery monsters: two giant eels, two jellyfish, four adult and hatchling black nagas each, and 14 random snakes; this may include pythons as capable of drowning you as the eels. Eight random objects and seven random traps are randomly placed. The crystal ball next to the kraken is underwater.
Note that depending on Medusa's position, you may be able to catch sight of her through the iron bars; take the appropriate precautions before nearing her complex.

This page is based on a spoiler by Dylan O'Donnell. The original license is:
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Strategy
The most difficult thing about reaching Medusa is crossing the water full of sea monsters. Levitation or water walking boots are the most common ways to cross the water. Using a wand of cold, a frost horn or the cone of cold spell to freeze a path across the water is another option, as is filling the water with boulders, or some means of jumping.
If you are trying to reach the island with boulders, you can push them to the stairs of the previous level and throw items to make them roll down. Alternatively, you can read preferably uncursed scrolls of earth if not enough boulders are available. At least eight boulders are needed for the first and fourth versions, 16 for the second, and a variable number for the third depending on which island spawns the down stairs. Fewer boulders may suffice if you're willing to jump repeatedly into a one-space water gap until you surface on the right side. However, since each boulder has a 10% chance of sinking without leaving floor, no amount of boulders is guaranteed to be sufficient to leave a path.
An amulet of magical breathing may also be used to traverse the level underwater, with all the effects that getting yourself wet entails.
If crossing the water is not an option, you may also opt to dig a hole to the next level and then come back up by using the staircase. The stairs to the next level are in the same room as Medusa, so make sure that you are ready for her before going up the stairs!

Origin

Wikipedia has an article about:
Medusa

The fourth variant of Medusa's Island draws in particular from some aspects of Medusa's tale in Greek folklore: After her decapitation, her spilled blood was said to have given birth to several creatures, including the Sahara's poisonous vipers and the venomous, twin-headed dragon-like serpent known as Amphisbaena. These are each represented by the abundance of snakes and black nagas, as well as the yellow dragon - black nagas, yellow dragons and their offspring are acidic and thus resistant to stoning. 
Similarly, the crystal ball may be an allusion to the Graeae, daughters of the sea-deities Phorcys and Ceto and sisters to the Gorgons. Perseus stole their sole shared eye in order to ransom it for information on the whereabouts of either Medusa herself or the three objects needed to slay her.

History
Medusa's lair first appears in NetHack 3.1.0. Before that version, she appeared in an ordinary room-type level. The previous series, NetHack 3.0.0, adds a number of statues to her room, but this is an ambiguous clue; it seems likely that many an adventurer met an untimely end from not knowing they would soon see Medusa. The use of telepathy or a potion of monster detection is advisable.
Nethack 3.6.0 adds two new possible layouts for the island.

Variants
UnNethack
As with other special levels in UnNethack, the four layout variations may be flipped horizontally, vertically, or both.

SlashTHEM
In SlashTHEM, there are far more sea monsters in the level (and other water levels). A few of these are new sea monsters with stealing and lycanthropy attacks. You should be prepared with ranged attacks and either telepathy or warning.

References

↑ dat/medusa.des in NetHack 3.6.6, line 56

↑ dat/medusa.des in NetHack 3.6.6, line 155

↑ dat/medusa.des in NetHack 3.6.6, line 273

↑ dat/medusa.des in NetHack 3.6.6, line 373

↑ dat/medusa.des in NetHack 3.6.6, line 320