I have no idea if this would work, but how about this?

Rather than the anomaly being created based on 1/Difficulty, how about the reward being determined by 1/Network hash rate at declaration of block reward?

You could then trigger the reward based on another factor, such as the last digit being odd, even, the number '3', etc.

The network hash fluctuates rapidly, unlike difficulty. The reward would still be announced at the start of the block, but as it could not be so easily predicted, the Multi-pools would not have as much time to 'swoop in' and steal the block. Similarly, as you can't accurately control the total net Hash rate, you couldn't force it to generate an Anomaly every time.

-T