Been playing a bard mage for past 4 years. I have some pretty decent spell casting ability. I am sure the PvM experience will not transfer well to PvP.
Never used a necro before though. Just training.
Um, the first creature I tried to fight with just pure necro was a sand vortex and it killed me. Then I tried to fight a summoned earth ele and it killed me. So, at necro, not so good.