2000 each army i think i'll go with a slann (life or light?) in a unit of temple guards with the razor standard and a big skrox unit (about 40 skinks and 3 kroxigor) but i don't know what to do with my 2000 points. Sallyes? Engine of the gods? Steggies? what can i do against demon princes?
Against HE & WoC, sallies should do well unless they go with all cav lists. Your vamp ally should be able to handle the DP between a combo of either terrorgheist screams and/or a totally kitted out vamp/strigoi lord.
I'd go Life Slann and give your Slann a Forbidden Rod. With a vampire ally you'll need all the power dice you can get.