Cool. I remember rogue. Too many caveats, though. I was thinking of making a rogue-like artifact where if you hit someone (melee or projectile) it disables their ability for 10 seconds. Prolly level 3 - don't want it to be super common.
I like the lifeline idea, but I think I'll make it two separate artifacts - one that drains others, one that heals others (just those on your team?). And... I'll prolly make it so it's just a simple radius. Everyone within 10 blocks gets the effect. Those are prolly level 3 because of their ability to affect groups.