Elanzo's Glittery Alarm

The caster of this spell winds a strand of silver wire across a doorway or a threshold. A glimmering dome of magical energy expands in a 100ft sphere. Any creature that crosses into this sphere,  intending harm, must make a Wis saving throw of DC 16. If the creature fails, their body begins to sparkle and shimmer in shades of red, brown, and green, alerting everyone within the sphere to the intent of the creature. If the creature passes the saving throw, no effect happens.