Vallakovich's Baleful Circle

As you cast the spell, you draw a 10-foot-radius circle on the ground, inscribed with sigils that look like coordinates to a location.

To a passive viewer, the circle looks identical to that of a teleportation circle spell, but upon closer inspection the color has a purplish glow and the sigils are gibberish. Any creature can make an Intelligence (Arcana) check against your spell save DC to determine whether or not this spell is a real teleportation spell. 

This circle remains on the ground and maintains it’s purple glow for the spell’s duration, after which the magic fades away, but the inscriptions remain engraved there indefinitely. Casting this spell on an already inscribed circle only takes 2 rounds to cast instead of 1 minute.

At any point during the duration and while you are within 100 feet of the circle, you may use your reaction to cause the circle to activate. This circle also activates if it is used in a casting of a teleportation circle spell. When it is activated, each creature within the circle takes 3d10 force damage. If this damage reduces any creature to 0 hitpoints, that creature is ripped apart and disintegrates into a flash of purple light.

At higher levels:

If you cast this spell using a spell slot of 5th level or higher, the damage increases by 2d10 for each level above 4th, and the duration of the spell is increased:

If you use a 5th level spell slot, the duration is 24 hours.

If you use a 6th level spell slot, the duration is 7 days. 

If you use a 7th level spell slot, the duration is 30 days. 

If you use a 8th level spell slot, the duration is 1 year. 

If you use a 9th level spell slot, the spell lasts indefinitely.