Maybe this is just obvious to everyone, But I wasnt sure for a while so I tested today. It seemed to be that perks cause the heal, but I wasnt too sure so I tested it.
So I attacked an adonis heckler, and let it take my health down (had to take off some gear and go full agg). Then I casted shades caress, went into crawl, and started firing off perks (you cant do normal attacks in crawl) Turns out the perks were healing me. I used the piercing mastery perks, so there would be no confusion as to what healed me (plus, the hp healed from perks is a different number than shades caress).
I suppose I could have used alien perks to test this out as well, but I didn't think of that at the time :P
Also, just some extra info on SC, the amount the attacker gets healed is affected by heal modifer%. SC heals me for 1560, rather than 1500. You will also notice this in vort, with that huge heal% buff.
Anyways, probably obvious to you guys, but whatever.