That is not the correct spell order for a short fight necro, a longer fight substitute dogs for bats, squeeze bats in somewhere else. For your level: +2 Grisly Mark +4.5 Pestilential blast +7 Ghastly Stench +8.5 Swarm of bats +10 Pestilential blast +14.5 Withering affliction +17 Pestilential blast +20.5 Locust Swarm +23 Pestilential blast +25.5 Bloody ritual +28 Pestilential blast +30.5 Ghastly stench etc. I haven't met a tank yet that couldn't handle that rotation, your tank needs to step it up if they can't.