Drain for gain
Drain for gain was a bug (SC343-10) that increases your maximum hit points and power by losing experience level (through some method of level drain) while having lower stats (in particular constitution and wisdom), then leveling up while having higher stats. By manipulating your stats before and after level drain, the amount of maximum HP and Pw you lose when losing levels could be made much smaller than the amount you gain when leveling back up.
In NetHack 3.6.0, this bug was fixed by recording the HP/Pw increase at each level. Draining a level will restore HP/Pw to exactly what it was before on each previous level, instead of reducing it randomly based on Constitution and Wisdom. This effectively nullifies this strategy for HP or Pw gain by using things that increases/lowers constitution or wisdom, though it could still be used to do things like buy protection cheaply, or to "re-roll" better HP/Pw increases after you've increased your Con/Wis since the beginning of the game.
At the beginning of the game, characters usually start with lower stats. Applying this strategy would allow your character to reach and exceed the maximum HP and Pw potential for average characters of the same level. It has effects comparable with or even surpassing those obtained through alchemy, nurse dancing and foocubi, without requiring the same resources.
This strategy also allows you to play the game as a relatively low level character (but with a lot of HP and Pw) for a long time. This has several advantages:
- You can buy a lot more protection more cheaply. Self draining to XL1 allows you a chance to buy protection for only 400 gold, this makes even naked AC -10 possible through donation if you have finished Ludios.
- If you don't want to buy any more protection, you can give half as much gold (while carrying no more than double the amount you give each time) to the priest for clairvoyance. An XL1 character spending only a few thousand gold on this may get enough clairvoyance to last through the entire game.
- You can reassign your skill slots.
- You can explore deeper dungeons while avoiding tougher monsters. Monsters with difficulty higher than (your level + dungeon level) / 2 are considered too strong to be generated. So if you drain yourself to XL1 before descending down every staircase, while keeping pets around to kill some monsters for you, you may be able to descend really deep with a much smaller chance of seeing tough monsters such as mind flayers.
- You may use the polyself bug.
Basically, if for any reason you want to drain your own level, you might as well try reducing your constitution and wisdom before doing so.
You will temporarily lower your maximum HP with each cycle; during the first cycle in the relatively early game your hp may become dangerously low. But after two or three cycles you will probably end up at XL1 with 40+HP, with at least 9 points of protection, making low HP a much lesser concern from then on.
When you have only limited method of reducing stats (e.g. cursed and non-cursed unicorn horn which is usually only good for 1-pt CON reduction), the effect of HP gain may not be very obvious (or sometimes even a slight HP reduction). But if you keep gaining several experience levels before draining, eventually you will find your maximum HP increasing. Switching to methods of greater stat reduction later in the game (e.g. rings of gain constitution) will accelerate your gain by a lot. You can combine multiple methods of stat reduction to achieve a greater effect. e.g. Applying a cursed unicorn horn while wearing a -2 ring of gain constitution until you get an extra -1 CON.
If you choose to lose level through a level-draining monster, you need to take caution not to die by over-draining yourself below XL1. This risk can be reduced by luring the monster into a controlled area (see below), zapping it with wand of slow monster, wearing an amulet of life saving, and/or using MSGTYPE if your game is compiled with it and you are using the tty interface. Consider putting the following lines in your options file:
MSGTYPE=stop "Goodbye level *" MSGTYPE=stop "Sayonara level *" MSGTYPE=stop "Fare thee well level *" MSGTYPE=stop "Aloha level *" MSGTYPE=stop "Farvel level *"
This will force a --MORE-- prompt every time you get drained a level. Then you could even hold down '.' next to a wraith without getting accidentally over-drained. Also always remember to replace MC-giving items immediately after you finish. You may need some pets around to protect you, or stop yourself to take care of other monsters that show up while you are draining levels. Gaining 1 or 2 experience levels when clearing distractions could be fine even without increasing your stats first, as you can drain them right back down afterwards, and having low stats means the fluctuation of maximum HP and power would also be relatively small.
If you choose to play as a low-level high-HP character for an extended period of time, there are also several disadvantages, but most of them can be mitigated:
- It might become more difficult to hit monsters. Having a blessed luckstone and maximizing your luck greatly improves your chance to hit.
- You may not have enough skill slots for spells. Simply drain level again to switch to a different spell class when you need it, gaining yourself a few extra points of maximum HP and power while doing so.
- You may die to monster's level drain attack more easily. Having MC3 makes this risk almost negligible, and having level drain resistance (e.g. by wielding Excalibur) removes this risk completely.
To use this strategy, you first need to find some methods of reducing stats, and a method of level-draining yourself. Then you need to find a way to increase your stats and level back up. In most situations, the resources for doing those only need to be obtained once, and then the cycle can be repeated indefinitely (and in some cases rather quickly, too).
The following methods can be used for reducing stats:
- Wearing a negatively enchanted ring of gain constitution to reduce constitution, or removing a positively enchanted one.
- Wearing a negatively enchanted helm of brilliance to reduce wisdom, or removing a positively enchanted one.
- Engraving on a co-aligned altar will reduce wisdom by 1 without any other penalty. You can easily reduce wisdom to the minimum of 3 this way. A cross-aligned altar will reduce your Luck instead.
- Quaffing a non-blessed potion of sickness as a non-healer will decrease one stat, even if the character has poison resistance. You can obtain potions of sickness from random alchemy.
- Applying a cursed unicorn horn. Two of the possible effects of a cursed unicorn horn are reducing constitution ("You feel fragile!") and reducing wisdom ("You feel foolish!"). You will need a way to cure other bad effects including sickness. Using a non-cursed unicorn horn would likely cure stat-losses as well, and therefore you may only be able to reduce your CON or WIS by 1 point despite repeated tries. Alternatively, using a cure sickness spell or blessed potion of healing to cure sickness may allow you to reduce stats lower. You can lock yourself in a closet and wait out all the non-sickness effects, though it may take a long time.
- Being seduced by foocubus while having low intelligence and charisma. Two of five possible negative effects reduce constitution and wisdom by one, respectively.
- Abusing them.
When your constitution is high enough, every extra point of CON reduction may have a large accumulated effect after draining multiple levels. So it might be worth the effort to get an extra point lower when you can (possibly through combining multiple methods above). See the table below for details.
Draining your level
The following methods can be used to drain your level:
- Throwing Stormbringer or The Staff of Aesculapius up and hitting yourself. Make sure you have enough HP to survive the hit. (You can wear a metal helmet to reduce the damage and draining will still take effect.)
- Removing MC-giving items and dancing with a level-draining monster such as a wraith, vampire or barrow wight. A relatively safe way to do this is to lure a wraith into a lockable room, engrave Elbereth in front of the door with an object on top, then stand diagonally next to the door outside so that when your level is low enough, you can just step away and the wraith won't ever come out.
(Hover over symbols for tips and links).
- Casting drain life at yourself.
- Dancing with foocubi at low charisma, which may either drain you or lower your stats further, both of which are actually desirable at this stage. However, even a negative result has the same chance of giving the foocubus a severe headache, rendering it useless.
The following methods can be used for increasing (or restoring) stats:
- Exercising them. Donating to priests for a lot of clairvoyance is a good way to exercise wisdom in the early game, as you exercise wisdom every 5 turns you enjoy clairvoyance.
- Applying a non-cursed unicorn horn to restore lost stats.
- Drinking a potion of restore ability, preferably blessed, to restore lost stats.
- Using the spell of restore ability to restore lost stats.
- Wearing a positively enchanted helm of brilliance, or removing a negatively enchanted one.
- Wearing a positively enchanted ring of gain constitution, or removing a negatively enchanted one.
Leveling back up
After fixing your stats, just kill some monsters to level up and watch as you get more maximum HP and Pw than before.
Stats and HP/power gain per experience level
The HP and Pw gain per experience level for different roles and races is covered in detail in . Constitution is the only character stat related to HP gain per level. The effect of maximum HP bonus per level due to constitution is summarized in the following table:
Wisdom is the only stat related to power gain per level. Every 2 WIS points has the approximate effect of adding d1 to the amount of power gain per level, this effect could be further multiplied depending on roles. (e.g. Wizards get a x2 multiplier.