Potion strategy

Which potions are valuable and which are not depends very greatly on your place within the game. When you first enter the dungeons, most potions provide some substantially useful effect. As you gain intrinsics or abilities, most become redundant or only marginally useful.

Recommended potions, in approximate order of desirability:

Table of potions

Always useful

Potion	Notes
full healing	When blessed, heals up to 400 HP and/or raises your max HP by 8; also cures sickness. Ascending with 6 or so provides a safe number of emergency outs, but save these for when you need them.
gain level	When cursed, teleports you up one level. Useful for Moloch's Sanctum, Gehennom and emergency escapes. Can also substitute for potions of gain energy in alchemy. In case you need the last few experience levels to enter the quest, quaff non-cursed.
holy water	Increments BUC status of #dipped objects. This provides the most reliable way to bless an object or uncurse items that get cursed during the ascension run.
smoky (can be any type)	Save, bless and quaff for the chance of a wish. A unicorn horn may be necessary to deal with ill effects.

Usually useful

Potion	Notes
extra healing	Mid-game emergency heal, otherwise save and alchemize to full healing. If potions of gain energy are scarce, you can quaff them for +5 max HP instead of alchemizing.
healing	Early-game emergency heal, otherwise save and alchemize to extra healing.
speed	Without speed boots, useful for difficult combat. Otherwise, alchemize with healing potions to make extra healing.
gain energy	Alchemize with extra healing potions to make full healing, or with full healing to make gain ability. Extras can be quaffed for a slight maximum energy gain.
gain ability	Bless to raise all attributes by one point when quaffed.
enlightenment	Alchemize with levitation to make gain level. Alternatively, bless and quaff to raise intelligence and wisdom by one point. Also useful to identify rings and amulets.
water	Bless or curse a stack to make (more) holy or unholy water, e.g. by dipping into your last one.
booze/confusion	Useful for confusing yourself, then reading a scroll of gold detection to locate portals on the four Elemental Planes. A forgotten spell is better; more than two, or an alternate source of confusion render these unnecessary.
paralysis	Throw or wield against powerful (sleep-resistant) enemies, then kill them before they recover.

Sometimes Useful

Potion	Notes
see invisible	If you do not already have the see invisible intrinsic, or in an emergency if blind.
invisibility	If you do not already have the invisibility intrinsic. Quaff one before eating a stalker to receive permanent invisibility and see invisible intrinsics.
unholy water	Decrements BUC status of a #dipped item. Useful for cursing scrolls of genocide, teleport, and destroy armor, and potions of gain level.
sickness	#dipped weapons will become poisoned. Lawful characters are penalized for striking with a poisoned weapon. Very useful with stacks of arrows and darts.
restore ability	Superseded by a unicorn horn, but guaranteed to work.
monster detection	Mostly superseded by telepathy. Useful for finding where that nymph teleported to. If blessed, lasts several turns and detects mindless monsters as well.
object detection	Locate the Castle wand of wishing. Useful when searching for Fort Ludios. For zen players, make stash seen.
levitation	Alchemize with enlightenment for gain level. A single blessed potion is enough for the endgame run. Can be used to cross Medusa's level if found in sufficient quantities.
polymorph	Can polypile a single of item.
oil	Recharges oil lamps, repairs weapon damage, untraps squeaky boards for pacifist experience. Throw lit oil for a Molotov cocktail.

Rarely Useful

Potion	Notes
fruit juice	Can be quaffed for a small amount of nutrition.
hallucination	Dip with a unicorn horn to make water. If you lack magic resistance (perhaps because of conducts), hallucination will protect against touch of death.
blindness	Dip with a unicorn horn to make water. Throw at monsters to give them a small to-hit penalty and negate some gaze effects. Quaff it yourself if you need to avoid a gaze and don't have a blindfold handy.
acid	Vegetarians can use these to cure stoning.

Finally, any potion can be diluted and blessed to make holy water. Water can be mass-alchemized step by step into sickness, juice, booze, confusion, enlightenment, gain level, and these further into healing, extra healing, full healing, gain ability, see invisible, hallucination. You will rarely alchemize the entire chain, but these potions are always available in case you need any.