Dipping items into a potion of amnesia has assorted mostly bad effects - magic tools and gray stones will become non-magical, weapons and armour will lose some enchantment and may be rusted or lose their rustproofing, and anything dipped into a potion of amnesia will become uncursed.
A potion of amnesia can be diluted to water with just one dip, but cannot be cancelled.
If you are (polymorphed into) a vampire, drinking a noncursed potion of vampire blood will give you the same amount of nutrition as a food ration (or half that if the potion is diluted), while ordinary noncursed blood will give you a small amount of nutrition. Cursed blood is congealed and has no nutritional value. A blessed potion of vampire blood will also increase your current and max hp by an equivalent amount to gaining an experience level.
If you are not a vampire, drinking vampire blood will polymorph you into one, with no timeout (you can return to your normal form by killing your vampiric form or polymorphing again and letting this new polymorph time out). Monks and Lawfuls will also anger their gods. Drinking ordinary blood will just make you vomit.
N.B. Invulnerability does not mean that you are completely immune to all types of damage. It only protects you against hit point loss (including some types of fatal damage, such as being bisected by the Tsurugi), deadly poison, death rays / touch of death, and black dragon breath (although your armour will not be saved by your invulnerability). It does not help against sickness, stoning, sliming, lost stats, brainlessness, lycanthropy, being level-drained, divine wrath, eating a Rider's corpse, and probably a myriad of other dangers.
Here's a table of possible upgrades:
| Original Object | Upgraded Object |
|---|---|
| Orcish dagger | Dagger |
| Dagger Great dagger | 1/2 chance of elven dagger 1/2 chance of dark elven dagger |
| Elven dagger Dark elven dagger | Great dagger |
| Knife | Stiletto |
| Stiletto | Knife |
| Axe | Battle-axe |
| Battle-axe | Axe |
| Pick-axe | Dwarvish mattock |
| Dwarvish mattock | Pick-axe |
| Orcish short sword | Short sword |
| Elven short sword Dark elven short sword Short sword | Dwarvish short sword |
| Dwarvish short sword | 1/2 chance of elven short
sword 1/2 chance of dark elven short sword |
| Broadsword | Elven broadsword |
| Elven broadsword | Broadsword |
| Club | Aklys |
| Aklys | Club |
| War hammer | Heavy hammer |
| Heavy hammer | War hammer |
| Elven bow Dark elven bow Yumi Orcish bow |
Bow |
| Bow | 1/3 chance of elven bow 1/3 chance of dark elven bow 1/3 chance of yumi |
| Elven arrow Dark elven arrow Ya Orcish arrow |
Arrow |
| Arrow | 1/3 chance of elven arrow 1/3 chance of dark elven arrow 1/3 chance of ya |
| Elven mithril-coat | Dark elven mithril-coat |
| Dark elven mithril-coat | Elven mithril-coat |
| Orcish chain mail | Chain mail |
| Chain mail | Orcish chain mail |
| Studded leather armour Leather jacket | Leather armour |
| Leather armour | Studded leather armour |
| Robe | 1/2 chance of robe of protection 1/2 chance of robe of power |
| Robe of protection Robe of power | Robe |
| Cloak of protection Cloak of invisibility Cloak of magic resistance Cloak of displacement Dwarvish cloak Orcish cloak | 1/2 chance of oilskin cloak 1/2 chance of elven cloak |
| Oilskin cloak Elven cloak | 1/4 chance of cloak of
protection 1/4 chance of cloak of invisibility 1/4 chance of cloak of magic resistance 1/4 chance of cloak of displacement |
| Fedora | Elven leather helm |
| Elven leather helm | Fedora |
| Dented pot | Orcish helm |
| Orcish helm Helm of brilliance Helm of telepathy |
Dwarvish iron helm |
| Dwarvish iron helm | 1/2 chance of helm of
brilliance 1/2 chance of helm of telepathy |
| Cornuthaum | Dunce cap |
| Dunce cap | Cornuthaum |
| Leather gloves | 1/2 chance of gauntlets of
swimming 1/2 chance of gauntlets of dexterity |
| Gauntlets of swimming Gauntlets of dexterity |
Leather gloves |
| Elven shield | 1/2 chance of Uruk-hai shield 1/2 chance of orcish shield |
| Uruk-hai shield Orcish shield | Elven shield |
| Dwarvish roundshield | Large shield |
| Large shield | Dwarvish roundshield |
| Low boots | High boots |
| High boots | Low boots |
| Large box Ice box | Chest |
| Chest | Ice box |
| Sack | 4/5 chance of oilskin sack 1/5 chance of bag of holding |
| Oilskin sack | Bag of holding |
| Bag of holding | Oilskin sack |
| Towel | Blindfold |
| Blindfold | Towel |
| Credit card Lock pick | Skeleton key |
| Skeleton key | Lock pick |
| Tallow candle | Wax candle |
| Wax candle | Tallow candle |
| Oil lamp | Brass lantern |
| Brass lantern | Oil lamp |
| Tin whistle | Magic whistle |
| Magic whistle | Tin whistle |
| Wooden flute | Magic flute (10-14 charges) |
| Magic flute | Wooden flute |
| Tooled horn | 1/3 chance of frost horn 1/3 chance of fire horn 1/3 chance of horn of plenty |
| Horn of plenty Fire horn Frost horn | Tooled horn |
| Wooden harp | Magic harp (10-14 charges) |
| Magic harp | Wooden harp |
| Leash | Saddle |
| Saddle | Leash |
| Tin opener | Tinning kit (70-99 charges) |
| Tinning kit | Tin opener |
| Crystal ball | Magic marker |
| Magic marker | Crystal ball (3-12 charges, unless marker had fewer) |
| K-ration C-ration Lembas wafer | 1/2 chance of
cram ration 1/2 chance of food ration |
| Food ration Cram ration | Lembas wafer |
| Loadstone | Flint stone |
| Flint stone | 1/2 chance of luckstone 1/2 chance of healthstone |