New Cantrip: Elemental* Trap

Abjuration Cantrip
Casting Time: 1 action
Range: Touch
Components: V, S
Duration: 1 hour
You touch a surface and create a magical trap of runes which triggers based on some prescribed effect. Once triggered, the trap explodes and deals 1d10 elemental* damage in a 5-foot radius around the trap. Anyone in the explosion can make a Reflex Saving Throw to negate the damage.
The trap fades if cast again or if you are more than 100 feet from the surface touched.
5th: Max two traps.
11th: Max three traps.
17th: Max four traps.

*Particular element? Fire? Acid?