Booby Trap
You set a schema which fashions and detonates an explosive device, based on a trigger, which is usually when a creature steps into the nominated area, but can be other triggers, such as a change in physical conditions, or any detail from a biometric scan.
The force damage from the trap when set off is equal to the conjugate effect roll. The creature may make an Agility save against your conjugate challenge, suffering only half the damage if they save.
You can exclude creatures from the trap by either using facial scans or other biometrics, or botnet tagging your allies.