It is not the critical but the special effects that count!

I am building an NPC and this one is a going to have a few unique spells. I am not one that goes looking for work to do so I am more than happy to take an existing spell, change the special effects and see how far that gets me. Now want I wanted was a spell that tearst he world apart and hurls it at the players, so nothing too spectacular.

What is the easiest way to do this?