Thoughts? Go fast. Turn. Stay upright. Win.
Generally I find rain crits to actually be not too bad. pack position is now more about being able to see and you find yourself willing to take some clean wind every now and then in order to clear your face and mind of the rooster tails you're getting slammed with. As mentioned the slickest part of rain is when it starts. If it has been raining for a while then I find I actually get pretty good traction.