At the beginning don't really go for kills unless you know for sure you're gonna kill them because Mord doesn't do much damage early on but later you'll be a great tank/caster/melee kind of character. Always use ignite and Children of the Grave together because they will do roughly 50% of their health.

The great thing about "Presence of the Master" (21 in utility) is it reduces ignite cooldown to near the cooldown of Children of the Grave, so its gonna help get you a lot of kills. I mastery him like a caster because he basically is one just that can tank great too, cheers!