I had looked over Repel and my judgment was thus: it feels overpowered and underpowered all at the same time. It also lacked an intricacy in making it worthwhile in the middle ranks.

My primary issue is the amount of creatures you can repel and under what circumstances. It forces a handful of enemies of up to your own rank to back off. Those half your rank and under and destroyed completely. All things considered, a rank no more than yours is underpowered and the half or less rank is overpowered. A rank 2 caster can wipe out an entire room without breaking a sweat.
Suggested Change: so what would I change? The answer is scope. This is a prime example of a good constructed spell. You choose the parts of it in order to achieve a final score:

  1. The base is choosing the strength - the maximum rank it can repel. Your own rank has no modification, below is +10 per rank and above is -10 per rank. If you're rank 3 and repel rank 5, it's at -20 while rank 1 is at +20.
  2. Once you decide the strength, you choose how many you can turn. I suggest an additional change here in the form of total ranks you can repel, as opposed to total enemies. That is to say: if you're rank 3 and roll a 6 on the 1D, you can turn a total of 9 ranks of enemies - 3 rank 3, 2 rank 3, a rank 2 and a rank 1 and so on. Start with 1D+CL and each 1D more is a -10 to the roll.
  3. Finally, is the force. This is how far they must stand. Start with 1D+CL again and each extra 1D is a -10 penalty.

Should be noted that you aren't seeing how to destroy things here. If it were up to me, there wouldn't be that option. However, if one insists, say it imposes a -20 to roll and can only be done on something half your rank.

The biggest change I have done here is allow the spell itself to work well outside the power of the character, if they can fuel it. A first ranker can repel a dragon, if they can cover for that -50.