There’s something very appealing about ritual magic. You don’t need to prepare it in advance and can cast it without burning a spell slot, so the only real costs are a few components and around ten minutes of downtime.

Of all the rituals to have stashed away in your spellbook, Alarm is one of the most consistently useful – if less dramatic – choices. After all, there isn’t too much regular demand for you to conjure up an Illusionary Script but it’s entirely possible that you be setting up a ward for your campsite every single night.

In essence, Alarm is one of those spells that does exactly what you expect it to do. When you cast it you set an invisible ward on a door, window or area just about big enough for the party to camp in. If anything crosses the boundary it sets off an alarm that can either be audible to everybody in range or to just you.

The area that the spell can cover isn’t huge so it won’t give you too much advance warning if any monsters, bandits or dire bears check out your band of sleeping adventurers, but unless the DM is feeling particularly cruel it should be enough to prevent the dreaded surprise round. While this won’t be useful every night, you can bet that you’ll be happy that you remembered it when a Drow Assassin comes slithering in through the window.

One of the best things about Alarm is that it doesn’t have any set component cost whatsoever. So long as you carry a focus or a component pouch with you and have it in your spellbook you can cast it as often as you like without having to spend anything at all.

There are plenty of times when overusing zero-cost spells can be a great way to slow down the game and annoy the DM – casting Guidance every time someone makes a skill-check, for example – but it’s easy enough to establish an Alarm ritual as part of your regular evening routine. Just remember that Dispel Magic and other spells can render your protection useless, so it’s still worth posting a watch when you’re in dangerous territory!

If you want to get creative there are even a few uses of Alarm that can do more than give you a good night’s sleep. Want to know when the Duke leaves his study? Alarm the door and set it so that you get a mental alert when it opens. Admittedly these covert approaches may need you to actually prepare the spell and burn a slot on it – hanging around the door with your ritual book out for ten minutes straight is a little suspicious – but can still be worth it if you construct your plan far enough in advance.

Rating: A-

An extremely solid spell that can help to keep you and your allies safe at virtually zero cost. Not particularly vital, but make sure to learn it if you can

Alarm (Ritual)

School: Abjuration
Level: 1
Casting time: 1 Minute
Range: 30 feet
Components: V, S, M (a tiny bell and a piece of fine silver wire)
Duration: 8 hours

You set an alarm against unwanted 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 tiny or larger 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 mental or audible.

A mental alarm alerts you with a ping in your mind if you are within 1 mile of the warded area. This ping awakens you if you are sleeping.

An audible alarm produces the sound of a hand bell for 10 seconds within 60 feet.