First off, I would like to welcome you to the forum! Second, I want to tell you that the thread name you posted is a good one. It fits that army. Now to your question.
At 1250 points, there are a few things you can do to prevent that spell from going off. It is either cracks call or the dreaded 13th spell. If it is the dreaded 13th it may be a little easier to stop. The easiest way to stop it would be to use the cube of darkness (or a dispel scroll) to stop the skitterleap spell. The cube has a chance to stop the magic phase (on a 4+). At 1250 points you could also take a slann, although it would be the very basic slann. Lore of light can buff against I tests using Speed of Light (I10 and WS10). You could also take becalming cogitation as your free discipline and deny his caster 6s to cast. I am assuming that when he skitterleaps, he is within 24 inches of your slann (if you take one).
While the slann does not have much protection, this may be your best bet. Because you cannot take any miscast protection (cupped hands), you should probably take the lore of Life.
Hope this helps.
If you have any other questions, please let us know.
