Add stress reducing to heal

So I’m making a custom healer class with custom skill sets. Particularly, a heal with a stress-level reducer when used on the target. Problem is, I don’t know how to do this.

If I were to add to my current skill code, how would I go about it?

e.g.: combat_skill: .id “omniscient_light” .level 1 .heal 5 7 .launch 43 .target @4321

How can I add a stress heal effect to my heal skill?