Alarm

A silent ward hangs over door, window, and threshold alike, waiting to betray the faintest trespass with bell or thought.

1st-Level Abjuration (Ritual)
Casting Time: 1 minute or Ritual
Range: 30 feet
Components: V, S, M (a bell and silver wire)
Duration: 8 hours

Alarm is one of the purest defensive spells in the game because it does not try to stop intrusion by force. Instead, it turns intrusion into knowledge. It watches a chosen threshold, chamber, opening, or measured space, and the instant an unwanted creature enters or touches it, the spell announces that fact. That single function makes it one of the most useful warding spells in any campaign built around stealth, camps, guarded halls, archives, tombs, shrines, treasury rooms, and dangerous sleep.

When you cast the spell, you choose a door, a window, or an area within range no larger than a 20-foot Cube. Until the spell ends, the ward alerts you whenever a creature touches or enters the chosen space. You can designate creatures that do not trigger it, and you choose whether the warning is audible or mental. The audible version rings like a handbell for 10 seconds within 60 feet of the warded area, while the mental version sends a psychic warning to you if you are within 1 mile, and that mental ping can even wake you from sleep.

That makes Alarm a spell of vigilance rather than punishment. It does not deny entry like Arcane Lock or punish trespass like Glyph of Warding. It gives notice. In play, that often matters more, because warning buys time, and time is one of the most precious resources in any dangerous place.

You set an alarm against intrusion. Choose a door, a window, or an area within range that is no larger than a 20-foot Cube. Until the spell ends, an alarm alerts you whenever a creature touches or enters the warded area. When you cast the spell, you can designate creatures that won’t set off the alarm. You also choose whether the alarm is audible or mental.

Audible Alarm. The alarm produces the sound of a handbell for 10 seconds within 60 feet of the warded area.

Mental Alarm. You are alerted by a mental ping if you are within 1 mile of the warded area. This ping awakens you if you’re asleep.

Why It Matters

Many low-level defensive spells are useful because they scale with caution rather than with raw damage. Alarm is one of the best examples. It costs only a 1st-level spell slot, can be cast as a Ritual, lasts 8 hours, and covers exactly the kind of spaces adventurers, temple guardians, scouts, spies, archivists, and paranoid magicians most care about securing.

It is also one of the best spells for making a place feel inhabited and defended. A tomb that merely contains treasure is passive. A tomb watched by Alarm feels claimed. A wizard’s tower that uses Alarm on the library door feels lived in by someone methodical. A chapel with a silent ward over the reliquary feels sacred because transgression is expected and prepared for.

Uses

Guarding Camps and Sleep

This is one of the spell’s oldest and best uses. Adventurers are vulnerable when resting, and Alarm lets them turn one entrance, one perimeter approach, one window, or one section of camp into a watched threshold. Because the mental version wakes the caster if asleep, it is especially effective for overnight security.

Securing Doors, Windows, and Hatches

Doors and windows are the obvious targets, and rightly so. A locked chamber is stronger when it is also watched. A hatch to a cellar, a shuttered archive window, a crypt entrance, a tower stair door, or a treasury grille all become more meaningful once crossing them is guaranteed to be noticed.

Watching an Interior Space

The spell’s 20-foot Cube option is what makes it especially flexible. It can guard a section of corridor, a ritual circle, a patch of treasure floor, a shrine alcove, a side chapel, or the space immediately around a bedroll or relic stand. That makes it more than a simple door spell. It is a spatial ward.

Silent Warning for Stealthier Play

The mental version is often stronger than the audible one. A bell warns everyone. A thought warns only the caster. That means a watchful wizard, ranger, or priest can learn of intrusion without immediately revealing that the intruder has been detected. In ambushes, espionage, infiltration defense, and temple watch duty, that difference matters.

Tactics

For Players

Use Alarm to protect what would otherwise be vulnerable because no one can watch it constantly. Campsites, back passages, hidden entrances, prisoner doors, treasure alcoves, and corridors leading to your fallback room are all strong choices. Because the spell can be cast as a Ritual, it is especially valuable when time is available and conserving spell slots matters.

Choose the warning mode according to your plan. If you want the whole group alerted instantly or want a public deterrent, use the audible version. If you want information without revealing that you have it, use the mental version. The mental alert is often the more tactically sophisticated choice, especially during sleep, infiltration, negotiation under threat, or any situation where hidden knowledge is better than public alarm.

Be careful about exclusions. The spell allows you to designate creatures that do not trigger it, so the difference between a useful ward and a nuisance often lies in whether allies, servants, familiars, guards, or summoned helpers have been considered.

For Dungeon Masters

Alarm is excellent for making places feel maintained rather than abandoned. A lich’s tomb may rely on harsher magic, but the abbey archive, noble records room, guild coffer chamber, wizard’s stair, and ranger outpost all feel more believable with quiet alert magic in place. The spell is not dramatic by itself, which is why it so effectively supports atmosphere.

It also creates scenes of decision rather than immediate violence. The intruder knows only if the audible bell rings. The caster may know without acting at once. That delay creates strong play: the guards wait in darkness, the priest quietly wakes the others, the wizard lets the trespasser come deeper, the ranger knows something touched the ward but not yet what it is.

Good Combinations

Arcane Lock

Alarm and Arcane Lock pair naturally. One warns of intrusion, while the other denies easy entry. A protected threshold becomes much stronger when crossing it is both difficult and certain to be noticed. This is especially effective on archive doors, reliquaries, prison gates, and treasury rooms.

Glyph of Warding

This is the classic progression of layered magical security. Alarm tells the defender that the boundary has been crossed; Glyph of Warding makes that crossing costly. Together they create both information and consequence. The pairing works especially well for shrines, tomb doors, trapped cabinets, and forbidden studies.

Mundane Guards and Traps

Because Alarm only informs, it becomes far stronger when other forces are ready to answer that information. A bell matters more if guards are near. A mental warning matters more if defenders have prepared chokepoints, missile fire, escape routes, or spells. Even mundane bolts, caltrops, dogs, or hidden sentries become more effective when Alarm ensures they are used at the right moment.

Sleep and Ambush Preparation

This spell is especially strong when used before rest or before receiving suspicious guests. The mental version can wake the caster from sleep, which makes it one of the cleanest low-level anti-ambush tools in the game.

DM Notes

Alarm works best when it feels like part of the life of a place. A monastery should guard its reliquary differently from a smuggler’s cellar, and both should feel different from a magistrate’s records room. The spell itself is simple, but the meaning of its placement is not. What people bother to ward tells you what they value, what they fear, and what they expect others to steal.

It also benefits from subtle telegraphing. A threshold swept too carefully. A window wired with tiny silver. A bell hanging where no breeze can reach it. A servant warned never to open a certain shutter after dusk. These details let players sense that they are in a watched place even before the spell is revealed.

Most importantly, use Alarm to create pressure, not dead ends. The spell should lead to chases, hurried whispers, broken plans, prepared defenders, and tense awakenings. It should not merely say “you fail.” It should say “you have been noticed.”

Why Alarm Works So Well in Play

Because forewarning is one of the deepest forms of power.

A hero who knows trouble is coming is already changed by that knowledge. Sleep becomes guarded. Corridors become meaningful. Silence becomes suspect. The spell does not need flame, thunder, or dazzling sigils to matter. It matters because it turns ignorance into readiness.

That is why Alarm belongs so naturally in camps, tombs, monasteries, guard towers, wizard studies, prison cells, reliquaries, archives, and treasure rooms. It is a spell of watchfulness, and watchfulness is one of the oldest defenses in fantasy.

Alarm

Alarm sounds a mental or audible alarm each time a creature of Tiny or larger size enters the warded area or touches it.

This material is Open Game Content, and is licensed for public use under the terms of the Open Game License v1.0a.

Abjuration
Level Bard 1, Ranger 1, Sorcerer/Wizard 1
Components V, S, F/DF
Casting Time 1 standard action
Range Close (25 ft. + 5 ft./2 levels)
Area 20-ft.-radius emanation centered on a point in space
Duration 2 hours/level (D)
Saving Throw None
Spell Resistance No

A creature that speaks the password (determined by you at the time of casting) does not set off the alarm. You decide at the time of casting whether the alarm will be mental or audible.

Mental Alarm A mental alarm alerts you (and only you) so long as you remain within 1 mile of the warded area. You note a single mental “ping” that awakens you from normal sleep but does not otherwise disturb Concentration.

A silence spell has no effect on a mental alarm.

Audible Alarm: An audible alarm produces the sound of a hand bell, and anyone within 60 feet of the warded area can hear it clearly. Reduce the distance by 10 feet for each interposing closed door and by 20 feet for each substantial interposing wall.

In quiet conditions, the ringing can be heard faintly as far as 180 feet away. The sound lasts for 1 round. Creatures within a silence spell cannot hear the ringing.

ethereal or astral creatures do not trigger the alarm.

It can be made permanent with a permanency spell.

Arcane Focus A tiny bell and a piece of very fine silver wire