Getting within three yards of whatever holds the trap triggers the trap, a flash of fire.
Detect: Per-based Thaumatology, or Perception + Magery for mages, at -5.
Circumvent: Automatic (don't go in the 3-yard radius).
Evade: Dodge at +2.
Effects: 1d-2 burning to everyone in a 5-hex radius.
A higher-level caster can cast this spell to do 2d+2 burning damage.