Alarm

1st-Level Abjuration (Ritual)
Casting Time: 1 minute
Range: 30 feet
Components: VSM (a tiny bell and a piece of fine silver wire)
Duration: 8 hours

You set an alarm against unwanted intrusion.

Target. A door, a window, or an area within range that is no larger than a 20-foot cube.

Effect. Until the spell ends, an alarm alerts you whenever a Tiny or larger creature touches or enters the warded area.

Special. 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.

At Higher Levels. When you cast this spell using a spell slot of 3rd or 4th level, the duration is 24 hours. When you cast this spell using a spell slot of 5th or 6th level, the duration is 30 days. When you cast this spell using a spell slot of 7th or 8th level, the duration is 180 days. When you cast this spell using a spell slot of 9th level or higher, the spell lasts until dispelled.

Source: PHB 211, SRD

Changelog

Added upcasting option.