I need a problem for my story. I have everything figured out for it except for the big problem. I need something along the lines of destroying the world (I know, typical). But something new, and something believeable and logical that I can work with. I have a necromancer in my story, and something associated with death, like the dead are rising would be interesting. But it has to be a really strong power, and I didn't think the dead would be strong enough. My main character controls earth, water, fire, air, spirit, energy and darkness, and eventually light. So I need something that poses a really hard challenge for her and her "parents". Anyone got any ideas??? Please?!

Storm control, like stopping a hurricane the size of Katrina. Stopping an Tsunami. Earthquake, maybe they can detect the big one coming and stop it. Meteor hit.  That type of thing.

How believable it is, well that is dependant on your writing skills. I've read murder mysteries that I did not believe due to the poor writing skills used. How hard is it to kill someone with a gun!

She's a necromancer, so how about the devil shows up, he wants the world and her soul.  He has the powers she has so it's a duel to see who is more powerful.   Gives you many ways to bring in excitment and thrills doing the things that xengab suggested.