ToME WikiSome very nasty monsters have weaknesses that can be used against them. This is often what separates the experienced player from someone who meets a monster for the first time.
Bats (b)
They rarely come close and are more of an annoyance than a threat unless they have breaths. Keep a shooter and ammo even if you're not very competent with it (slings are light and OK) and you'll be doing fine. Noxious cloud wands help.
They also will not run past you, so they can be backed into a corner and killed.
Breeders (I l r j , h w)
Noxious cloud wands will kill most of them quickly before they spread. If you're worshipping Yavanna or are a geomancer, the very large area covered by the Vapor spell will be a godsend when dealing with arena levels with a breeder problem.
Breeding j's are kind of slow and since they don't move it restricts their breeding. Beware of their stat-lowering effects, though.
A few leprechauns(?) breeders use the symbol 'h' and will breed, steal stuff, and teleport far away. Make a priority to kill them all on sight, as they may teleport as their first move and quickly fill out the entire level! Fortunately they don't have many HP.
As most breeders don't drop treasure, don't feel guilty genociding them!
Be careful with Genocide if the breeders have had a while to get going. I have lost decent characters to the 'backlash' even on small levels.
Demons (u U)
Anti-summoning corridors, scrolls of *Destruction* help in case of non-burrowing demons.
Weapons of *Slay demon*, genocide will help.
Dragons (d D)
Close the door if you just wish to avoid them - it usually works.
Anti-summoning corridors are the only known weakness of dragon-summoners. Get the appropriate resists and quaff a potion of resistance to resist their breaths.
Genocide and scrolls of *Destruction* help.
Effects that can polymorph them (polymorph rod, chaos thaumaturgy, chaos scrolls) are useful against dragon kinds you can't resist the breath of.
Hounds (Z)
Close the door if you just wish to avoid them - it usually works.
They won't melee you if you have all your hit points; after some harm they will go after you (this is nasty when you're surrounded by clear hounds but you don't know it yet). You can get harmed on purpose to get them close to you and kill them in a corridor corner one by one easily enough.
If you're resisting their breaths well, they're not very dangerous.
Most area attacks can kill most hounds without a problem, but usually one kind of hound resists each attack that can be resisted.
Time hounds are very nasty (huge stat loss regardless of resists) unless you wear the anchor of space-time.
Resistance to sound or Antimagic fields prevent being knocked-out by Water Hounds.
As they don't drop treasure, don't feel guilty genociding them!
Hrus (P)
They can't cross water; use a wand of tidal wave to completely avoid melee and still shoot or cast at them.
They can be confused/charmed more easily because they're flagged "stupid" in the code (it still takes a while to get it done). They're vulnerable to rock removing attacks such as wands of dig (but those don't do much damage considering the huge about of HP they have).
Polymorphing them usually turns them in something you can kill in a few rounds without quake-wrecking the dungeon with their 'shatter' effect.
Lich (L)
Drop any unneeded wands before doing the library quest or fighting most liches; they can heal themselves by draining your wands and it's hard to kill them if they heal all the time. Also, they teleport when in trouble - use the anchor or some strong "finishing move".
Nazgul (N)
Weak to light. A junkart of light absorbtion (when surrounded by as much lighted squares as possible, not by dark squares or buildings) will kill the Bree quest Nazgul or at least harm it a lot.
They can't cross water; use a wand of tidal wave to completely avoid melee and still shoot or cast at them.
The Bree quest Nazgul has no distance attacks at all; you can get a shooter or two, buy stacks of ammo or switch shooter as needed, and slowly shoot it dead if he can't reach you (i.e. water in between, speed, some attack that pushes it away, surrounded by trees and one of the moat(?) square you can shoot over, or a large number of non-moving pets as a temporary buffer).
Dropping your other stuff on the floor so you're not slowed by weight when shooting 99 bolts at the water-cornered Nazgul can also help as he won't get as many turns to regenerate some HP.
Non-moving (Q m j e , &)
Newbies need to remember that getting next to a floating eye usually means paralysis until death. Get a lantern so you can avoid getting paralyzed before you can react. And do remember to react by not going closer to it!
& is for mimic, it's what they look like when you detect them but not the object they mimic. For genocide and beastmaster purposes, they count as a 'm'.
Most of those monsters are vulnerable to light. It's easy enough to get behind any kind of obstacle and heal before you continue fighting them.
Deathmolds are completely harmless if you don't get next to them.
Q's are easy targets if you can prevent their teleportation by wearing the anchor of space time.
Moldoux shouldn't be killed unless you want to be fighting chain-summoning great wyrms of power and get only dungeon level 1 treasure for it.
Drujs if damaged will teleport you away on sight - use anchor or superior speed.
Orcs and Ogres (oO)
Generally vulnerable to invisibility. 'O' are stupid and vulnerable to most mind magic and confusion scrolls.
Spiders (S)
Spiders are often weak, but some are very nasty casters. Some are damaged by light. Having at least fire resist doubled with a potion of resistance (and also high saving throws) is needed for the Mirkwood Spiders quest.
They're usually poison resistant, so use other longeffect/area attacks as they don't have many resistances.
Effects that can polymorph them (polymorph rod, chaos thaumaturgy, chaos scrolls) are a good defense against very powerful casters.
Thunderlords (B)
The anchor prevents them from using a hit-and-run tactic on you.
Trolls (T)
They can't cross water except for water trolls and some uniques; use a wand of tidal wave to completely avoid melee and still shoot or cast at them. You can also melee them one at a time when they're cornered by water.
Uniques (varied apparence)
Artifacts of light absorbtion can kill low level uniques (including some weak Nazgul) in one shot provided you are surrounded by lots of lighted floor squares. Some potions you wouldn't quaff are good for throwing at them to produce some effects rather than just damage. Rods of slow monster are good if you know the combat will be long or if it tries to flee (that rod also slows the casting/summoning rate).
Against many low level uniques, scrolls of monster confusion are worthy as you'll get hit less.
Genocide is useful against mass summoners. If all else fails, a *destruction* scroll will get you some instant anti-summoning corridor.
Uniques cannot be polymorphed or genocided.
Vortex (v)
They have low hit points. Most can be hit in melee safely. They can be fled because they're too erratic to chase you well.
Chatter
AgEnt: Just a question about the mimics - I thought that they were also represented by m - you can get them with the grow molds power, and they appear under identify symbol (/) as a yellow m.
True, and I think they're genocided under 'm'. The & is just an inconsistency that fooled and killed me twice (I should have read my own spoiler after the first one!).
FeathinSilyar: Yeah, I genocided them with 'm' very recently. Makes the last Lothlorien quest very easy. Three genocides and the entire monster swarm is dead.
SimonSorc: this is worthy of making/adding spoiler to this quest.
Hypnos: Some monsters have actual vulnerabilities - Giant Rocs are weak against Acid, Red Dragons can be hurt by cold, White Dragons can be hurt by fire. Eol and Maeglin can be confused which is rare for uniques that are that powerful. Wavelords and Ents are also vulnerable to fire. Druj, Quythulgs, and some other monsters have no melee attacks. Many undead, jellies, orcs, trolls, and other monsters are vulnerable to light. Very high dex will stop enemies who can hit to steal things.