# Energy
Your power, or "Pw", is the amount of magical energy you have.  For example:

Dlvl:3  $:43  HP:68(68) Pw:13(18) AC:-3  Xp:8/1295 T:2358

The above status line shows a character whose current power is 13 and maximum power is 18.

Contents

1 Uses of energy
2 Gaining energy

2.1 Specific methods
2.2 Energy regeneration
2.3 Level gain and starting energy

3 Variants

3.1 SLASH'EM
3.2 FIQHack

4 References
5 External links

Uses of energy
The main use of energy is to cast spells.  You need 5 times the spell's level of energy to cast a spell.  When carrying the Amulet of Yendor, there is an additional random cost. This cost applies only to spellcasting, not to any other expenditure of energy. See spellcasting cost for more details.
Teleportation at will from teleportitis requires 20 energy, but only consumes 19.[1]  The usual random teleportation from teleportitis does not use energy.
Certain #monster commands require energy. The breath weapons of dragons, iron golems, winter wolves and hell hounds all cost 15 energy.[2] Summoning help as a werecreature[3] and emitting psychic blasts as a mind flayer[4] both cost 10 energy.

Gaining energy
You normally regain energy slowly over time, unless your encumbrance is Stressed or worse, which blocks normal energy regeneration.  Having the Eye of the Aethiopica allows you to regain energy rapidly, even when stressed.

Specific methods
Quaffing a non-cursed potion of gain energy increases your current and maximum energy; a cursed potion decreases them.
#invoke the Mitre of Holiness to regain half the energy you need to reach the maximum, but no more than 120 points.
Reading any scroll of charging while confused recharges your energy to its maximum.  If it was already maximum, you gain 5d4 total energy instead.[5] In 3.6.0 or later cursed scroll will reduce energy to 0 without altering the maximum “You feel discharged.”
Eating a newt corpse sometimes increases energy by 1 to 3 points.  If this would put you over the maximum, your maximum energy might also increase by 1.
If you trigger a magic trap and it explodes, “Your body absorbs some of the magical energy!” and your maximum energy is increased by 2; your energy is then completely refilled.[6]
Attacking a spellcasting monster with Magicbane has a chance of cancelling it and increasing your current and maximum energy by 1 (“You absorb magical energy!”)[7]. Only the cancellation from Magicbane can absorb energy. This effect happens every time the cancellation attack hits, not just the first time, when the monster is actually cancelled.
Lying with a foocubus may increase or decrease your energy.
The polyself bug can be exploited to increase your maximum energy exponentially.

Energy regeneration
The rate at which energy regenerates over time increases with your experience level, wisdom, and intelligence.  If your encumbrance level is Stressed or higher it will not regenerate.
Your energy normally regenerates every  turns if you are a Wizard, and every  turns for other roles.[8]  If you carry the Eye of the Aethiopica, you regenerate energy every turn regardless of role.
The amount of energy regenerated each time is between 1 and , which for most characters means 1d2 or 1d3. Increasing that to 1d4 requires a well-enchanted helm of brilliance since no playable race has Wisdom and Intelligence caps high enough to reach a total of 45.
Number of turns between regenerating energy:

Level

Non-wizard

Wizard

1
24
18

2
24
18

3
23
17

4
22
17

5
22
16

6
21
16

7
20
15

8
20
15

9
19
14

10
18
14

11
18
13

12
17
13

13
16
12

14
16
12

15
15
11

16
14
11

17
14
10

18
13
10

19
12
9

20
12
9

21
11
8

22
10
8

23
10
7

24
9
7

25
8
6

26
8
6

27
7
5

28
6
5

29
6
4

30
5
4

Level gain and starting energy
When you gain a level, both your current and maximum energy are increased based on various factors:[9]

your role
your race
your Wisdom
your experience level
First, a random number  is chosen;[10] your race minimum is then added to the result.[11]
Your role modifier depends on whether your experience level (before the level gain) is lower than a certain cutoff which varies between roles. If it is, apply the "low-XL" modifier; else use the "high-XL" modifier.
The result of this is then multiplied with your energy modifier, which depends on your role, and rounded down.[12]
The final result will be added to both your current and maximum energy.
For a newly created character neither energy modifier nor Wisdom matters[13]: certain magically inclined roles start with a few energy points at random, while others only get one point; all races except Dwarves also get a bonus point or two.  See the table below for precise numbers.

Role

Cutoff

low-XLmodifier

high-XLmodifier

energy modifier[14]

starting

Arc
14
1
1
1
1

Bar
10
1
1
3/4
1

Cav
10
1
1
1
1

Hea
20
1
2
3/2
2-5

Kni
10
1
2
3/2
2-5

Mon
10
2
2
1
3-4

Pri
10
2
2
2
5-7

Rog
11
1
1
1
1

Ran
12
1
1
1
1

Sam
11
1
1
1
1

Tou
14
1
1
1
1

Val
10
1
1
3/4
1

Wiz
12
2
3
2
5-7

Race

minimum gain

starting

Human
2
+1

Elf
3
+2

Dwarf
0
no bonus

Gnome
2
+2

Orc
1
+1

Variants
SLASH'EM
Self-teleport costs 30 points of power.[15]
The energy regeration frequency formula is changed to  turns if you are a Wizard, and every  for all other roles.

FIQHack
There are numerous changes to energy and energy regeneration in FIQHack.

Monsters and players use the same spellcasting system, which means that monsters use energy to cast spells instead of using a cooldown system.  This means they can potentially cast multiple spells in succession if they have enough energy, so high-level spellcasting monsters can do much more damage.
Wisdom is slightly less important for energy regeneration and experience level is slightly more important.  Intelligence is not considered.
Wizards get a boost of +0.33pw/turn for energy regeneration
The Eye of the Aethiopica confers +1pw/turn for energy regeneration
Players can be cancelled, which results in 0 available energy until cured.

References

↑ teleport.c in NetHack 3.4.3, line 517

↑ polyself.c in NetHack 3.4.3, line 748

↑ polyself.c in NetHack 3.4.3, line 910

↑ polyself.c in NetHack 3.4.3, line 1075

↑ read.c in NetHack 3.4.3, line 1056

↑ trap.c in NetHack 3.4.3, line 1058

↑ artifact.c in NetHack 3.4.3, line 844

↑ allmain.c in NetHack 3.4.3, line 211

↑ exper.c in NetHack 3.4.3, line 195

↑ exper.c in NetHack 3.4.3, line 196: The function also considers a race modifier, but this is 0 for all races.

↑ exper.c in NetHack 3.4.3, line 197: This also considers a role minimum, but this is 0 for all roles.

↑ exper.c in NetHack 3.4.3, line 201

↑ newpw in exper.c

↑ enermod in exper.c

↑ SLASH'EM_0.0.7E7F2/teleport.c, line 790

External links
HP and power starting values, level increases, and regeneration in NetHack 3.4.3

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It may contain text specific to NetHack 3.4.3. Information on this page may be out of date.
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