Medusa's Island

Medusa's Island
Location	Level 21–28 of the Dungeons 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, also known as Medusa's lair, 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.

The level is called "Medusa's lair" the only time the game directly names it to the player (when seeing it through an applied a crystal ball), but other comments in the source refer to it as "Medusa's island".

Generation

Medusa's Island is always 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 map, each of which has an equal chance of being used, and the chosen map may also be flipped horizontally and/or vertically—the map descriptions below assume that no flipping has occurred.

Common traits

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

• A historic statue of a knight named Perseus, with independent probabilities for the following items.
  • a cursed +0 shield of reflection, which has a ¹⁄₄ chance (25%) of being placed on the second map and a ³⁄₄ chance (75%) otherwise
  • a 25% chance of a +0 pair of levitation boots, which has a ³⁄₄ chance (75%) of being placed on the second map and a ¹⁄₄ chance (25%) otherwise
  • a 50% chance of a blessed +2 scimitar
  • a 50% chance of a sack
• Empty statues of random monsters placed around the level.
  • On the first map, there are seven statues placed in random locations.
  • On the second map, there are eight statues placed on specific squares.
  • On the third map, after Medusa is placed on one of three specific squares, one of the statues will occupy one of the two remaining squares, while the other six are placed in random locations.
  • On the fourth map, after Medusa is placed on one of four specific squares, one of the statues will occupy one of the three remaining squares, while the other six are placed in random locations.
• Five empty statues of player monsters with names and roles selected from the top-ten list in the same room as Medusa.

First version

Medusa's Island (1)
Location	Level 21–28 of the Dungeons 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, and the doors to her room are locked. There is a random snake placed on the squeaky boards in each of the top and bottom corridors, two water trolls on the marked squares to the right of the central island, three giant eels and three jellyfish on the marked squares to the left of the central island, and ten other random monsters. In addition to the two marked squeaky boards, there are five other random traps on the level. Eight random items are placed across the islands, and two more random items are placed on the squeaky boards where the snakes generate.

Second version

Medusa's Island (2)
Location	Level 21–28 of the Dungeons 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 asleep on the down stairs with the statue of Perseus. In contrast to the other versions, the probabilities of the shield and boots in Perseus' statue are 25% and 75%, respectively. Eight statues of random monsters are placed to the left of Medusa's room as marked.

The other monsters on the level consist of: a titan and a gremlin in the unlit entrance hall; six electric eels and three jellyfish on the marked squares just off the coast of the entrance island; four stone golems and two cobras sleeping among the monsters statues immediately outside Medusa's room; a random A and a yellow light in the unlit back room of Medusa's hall with the locked door; and thirteen more random monsters distributed fairly evenly across the islands of the level. In addition to the marked magic trap, there are four other random traps on the level. Six items are placed randomly across the level.

There are marked boulders in the entrance room and on the right-hand island—the latter has a random wand placed beneath it. The walls of both the entrance hall and Medusa's hall are undiggable.

Third version

Medusa's Island (3)
Location	Level 21–28 of the Dungeons of Doom
Bones	No
Mappable	Yes
Teleportable	No
Diggable floor	Yes
Diggable walls	some

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This level is "shortsighted", meaning monsters can only see you when you approach within a certain radius.

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 the sleeping Medusa and the statue of Perseus on the same square: once those are placed, one of the remaining locations will have a random statue placed there, while the other will have a fountain. Six other random statues are dispersed across the level. The rooms where Medusa can be placed are unlit and have non-diggable walls, but the right half of the double room (excluding its left wall) is diggable, and the trees on the level can be chopped down. All doors will be locked except for the first door leading into the double room, whose state is randomized.

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 southern-most island as marked, and eight random items are scattered around the level. Two rust traps, two squeaking boards, and one other trap are randomly placed.

Fourth version

Medusa's Island (4)
Location	Level 21–28 of the Dungeons 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. The sleeping Medusa dwells within her "palace" on the left, with the down "stairs" marked above serving as locations where the actual down stairs can be generated: Medusa and the statue of Perseus will always be placed on the down stair's square, and one of the three remaining squares will have a random statue. Six other random statues will be placed across the level.

The marked yellow dragon is generated asleep at the marked location, and may have up to two babies sleeping by them: the one to the adult dragon's left has a ¹⁄₂ chance (50%) of being placed, while the one below that has a ¹⁄₄ chance (25%) of being placed. The adult dragon also nests atop one to three yellow dragon eggs, with the second having a ¹⁄₂ chance (50%) of being placed and the third having a ¹⁄₄ chance (25%) of being placed; these eggs may hatch into awake and hostile baby yellow dragons by the time they are reached. Also inhabiting the level are various, mostly slithery monsters: two giant eels, two jellyfish, four black nagas and black naga hatchlings each, and 14 random snakes—the snakes may include pythons that are as capable of drowning a hero as the eels. A crystal ball is placed next to the kraken underwater at the marked location, and eight random objects and seven random traps are randomly placed across the level as well.

Note that depending on Medusa's position, it may be possible to catch sight of her through the iron bars—players are advised to take the appropriate precautions before nearing her complex.

Strategy

A user has suggested improving this page or section as follows:

"expand on the boulder-related strategies, taking all four maps into account, perhaps specifying where the boulders go; explain how to dig down on variants where there's no room; discuss what forms of jumping are needed for which maps"

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 maps, 16 are needed for the second, and a variable number are used for the third depending on which island the down stair is located on. Fewer boulders may suffice if you're willing to jump repeatedly into a one-space water gap until you surface on the right side. Since each boulder has a ¹⁄₁₀ chance of sinking without leaving a floor square, there is no set minimum amount of boulders that will always 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—be absolutely sure not to dig on a water-adjacent square, or you are likely to drown. Additionally, remember that the down stairs to the next level is in the same room as Medusa, and make sure that you are ready for her before climbing back up!

History

Medusa's Island and its initial two layouts first appears in NetHack 3.1.0. From Medusa's debut in NetHack 2.2a to NetHack 3.0.10, Medusa is found on an ordinary room-and-corridors level—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 when playing these versions.

The random wand under the boulder in the second layout is a reference to NetHack 2.2a and NetHack 2.3e: in these versions, a wand of wishing is guaranteed to be found in a dead-end square of the first maze below Medusa's dwelling, with an enormous rock on top of it. NetHack 1.3d, which does not have Medusa, similarly has a wand of wishing placed under an enormous rock on a dead-end square of every maze level.

The third and fourth layouts of Medusa's Island are added in NetHack 3.6.0. From this version to NetHack 3.6.7, including some variants based on those versions, these layouts place the statue of Perseus at one of the potential Medusa locations that is not chosen during level creation. NetHack 5.0.0 moves the statue back to Medusa's square, but adds a random statue at another location so that object detection won't reliably locate the down stairs.

Origin

The fourth variant of Medusa's Island draws from some aspects of Medusa's tale in ancient Greek folklore: After Medusa's 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 the Amphisbaena. These are each represented by the abundance of snakes and black nagas placed on the map during level creation, as well as the yellow dragon—black nagas, yellow dragons and their offspring are acidic and thus resistant to stoning.

Similarly, the crystal ball placed on this map 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.

Variants

UnNetHack

As with other special levels in UnNetHack, the four layout variations for Medusa's Island may be flipped horizontally, vertically, or both.

A magic portal to Fort Ludios will be generated on Medusa's Island if a portal is not generated in an eligible vault prior to reaching this level.

dNetHack

In dNetHack, notdNetHack and notnotdNetHack, the 'challenge' level generated before the Castle may either be the Grue's Cavern with a ¹⁄₃ chance or Medusa's Island with a ²⁄₃ chance; Medusa's Island has all four layouts from vanilla NetHack, including the two additional layouts that were obtained from a patch prior to their inclusion in NetHack 3.6.0.

Three Gorgoneions can be found burned into random squares on Medusa's level.

SlashTHEM

In SlashTHEM, there are far more sea monsters in the level, including mermaids with theft attacks, making ranged attacks, telepathy and/or warning more important to have by that point.