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Can i create a spawn who operate when a player in proximityrange have a skill (mining) => of a number (es 70)?
yes. Configure the spawner for proximity triggering (set ProximityRange to a value zero or greater) and set the PlayerTrigProp on the spawner to whatever player property test for triggering requirements you would like. For a skill requirement set it to a string like
SKILL,mining>100
or
skills.mining.value>100
or
skills.mining.base>100
or
skills.mining.cap>100
depending on what you want.
"SKILL,mining>100" is the same as skills.mining.value>100
You probably also want to set either the SpawnOnTrigger property to true, or set a small min/maxdelay value.