If you feel you've spammed your skills and haven't put a dent in the opponent, you'll most likely need to check your gear/level/health/mana and what not.

I've had some successful games with Erebus where batswarm and bit have crippled opponents. Not that this is a part of the build but I do recall grabbing a point in the mist skill merely because I wanted to give additional time to my cooldowns to pop out, and in most cases the ai/players will usually move out of the mist - giving you more time to gani some distance if you need to run.

I'd only advise one point into it as the skill keeps you stationary and drains too much mana after, but it is still a decent skill to regain your breath and composure. Just an alternative you can try but again, the Batswarm - Charm - Bite and beat to a pulp approach have worked decently well.

And make sure to invest points to get vampiric aura late game...Again these are all in guides but I can already guess pre-printed text may not provide you any comfort.