Berserk
Going into a berserk rage grants you Might, Haste, and roughly a 150% boost to HP (including max HP), all of which makes you a terror in melee combat.[1] However, it disallows any action unrelated to fighting, moving, butchering, praying, and eating. It lasts about 20 to 40 turns, but the duration rapidly decreases[2] if not fighting or butchering.
Afterwards, it causes you to become slow and exhausted (can't go berserk for awhile), and you may pass out from overexertion. Going berserk also has a food cost of about 600 units. Note that the exhausted status is the same as the one from casting Death's Door - one cannot cast that spell immediately after berserking, and vice versa.
You cannot use the ability from Trog or evoke it from an amulet or randart if you're Very Hungry or worse. The rage duration may be extended on kills if you're wearing an amulet of rage or worshiping Trog, possibly leading to haste/might magic contamination if done excessively.
The chance of passing out after your rage is 1 in: 10 + (rage_mutation_level * 25) + (10 if wearing amulet of rage). If worshiping Trog and not penitent, there's an additional piety-in-150 chance of not passing out. You'll never pass out if Xom made you go berserk. If you worship Cheibriados and have the berserk mutation, Chei will prevent the haste effect.
Berserk monsters are impervious to fear.
Sources of berserk
You can go berserk from the following:
- Trog's "Berserk" invocation.
- The amulet of rage.
- The potion of berserk rage.
- The "You tend to lose your temper in combat" mutation will randomly drive you berserk in combat. The chance varies (1%, 3%, 9%) with the mutation level, and the chance of passing out decreases.
- Some artefacts randomly cause berserk status (similar to the above mutation), while others let you evoke it at will (similar to the amulet).
- Drawing the "Berserk" card from a deck.
- A moth of wrath can drive you (and other creatures) berserk.
- It is also a Charms and Hexes miscast effect.
Some conditions prevent going berserk:
- Wearing an amulet of stasis or amulet of clarity, or having any other source of clarity or stasis.
- Being exhausted from a previous rage or casting Death's Door
- Being undead. For players, this means being a Mummy or Ghoul, a Vampire with less than full satiation, or in lich form. ("You cannot raise a blood rage in your lifeless body.")
- Being very hungry will prevent going berserk from Trog's invocation or any item that allows you to evoke a berserk rage.
Strategy
Do note that the berserk status also sets your stealth to zero. While this might be no difference for a Troll, stealthier characters might want to consider this; as this can very well draw more monsters to the berserker as that one can handle before their berserk runs out.
A potion of speed will counter the slowing - an excellent tactic if you find yourself exhausted while still in combat. Elyvilon's "Purification" is also effective.
If none of these options are available, think carefully before going berserk. It's a good idea to retreat to an open-area staircase beforehand, so you can escape in case a monster approaches while you're slowed. Summoning allies (incidentally, another of Trog's given powers) also increases your chances of survival if your rage expires while you are still in combat.
History
The Berserker Rage spell used to also give berserk, but it was removed in 0.9
