EARLY GAME How to kill -> 2-nd spell + heavy melee (315) + 1-st full charge (395) = 710 damage
MID Mystic + vuln + shred items combo prepare -spirit res for combo. After fully buying this link combo is: bullet hit + phantom + silence + light melee + CF + 1-st skill. I prefer this over necroses course, since without scripts it's take a time to use it all and doing his route makes more space for target to react. Note: I usually buy CF -> Phantom -> Silence. You can buy silence before, but since it has travel time and speed, it usually only works if you need it ASAP vs Pocket/Gheist/etc.
LATE Now combo extends a little: Invis -> bullet hit (HEADSHOT ONLY if you take crippling) -> phantom -> silence -> melee -> CF -> 1-st skill -> 3-rd skill -> just bullet spam. If target is not dead yet: just spam bullets and use 2-nd to slow him again. Note for scripters: if you use active items script, the right order is CF -> Silence -> Phantom. In any other order, you won't be able to cast Silence/CF during Phantom Strike animation