Can you suggest what are some cool mutations (preferably co-dom or dominant) that can be added to a killer bee?

The reason I ask is, at first, I wanted to breed killer bees, so I was planning to get a bumble bee male and breed it to a pastel female. However, my collection has progressed, and I now have two super pastel females that I am raising up (they are also het for genetic stripe). At first I was going to pair them up to a male killer bee, so the odds of getting a killer bee would be much greater than originally planned.

However, getting a killer bee to breed killer bee, seems, well, boring now. So wonder what I should go for to pair with my super pastel het g stripes? May as well get a gene that I don't have yet, instead of getting the killer bee with super pastel I have plenty of pastel. So maybe a bumble bee something, or a killer bee something? What would be a cool combo?