Rage eruption
Rage eruption is a technique that appears in SLASH'EM, SlashTHEM and Hack'EM. It is similar to the MP-increasing power surge technique.
Description
When activated, the technique your character's current and max HP by 50 + (4 * TECHLEVEL), then decreases them by one every turn; you cannot go below 1 HP from any health lost this way. The technique lasts for 50 + (4 * TECHLEVEL) turns - once it ends, your max HP is set to its previous value.
This technique is exclusive to dwarven characters, and is unavailable while a character is polymorphed.
Strategy
Although rage eruption is a very powerful technique that can save the lives of many dwarvish players, it has to be used with care - you will end up at 1 max HP, rendering healing impossible until the technique ends. After disposing of the monster(s) that prompted the use of a rage eruption, it is wise to run upstairs and/or engrave Elbereth to avoid being killed while at low HP.
Also, beware of koalas when using rage eruption - their otherwise harmless touch will abort the technique instantly, robbing you of all your extra HP in the middle of battle.
Rage eruption is also useful for reliably activating the limit mode on other techniques at 1 HP.