So, you want an alliance with the Skaven?

Step One: Play Skaven

Step Two: Ally with somebody else.

That's about as close as it gets. Sneaky rat bastards. (fuming ragequit for ratling shennanigans)

What's the worst way they backstabbed you? My vampires loved the idea of plagues and vermin around them. Liked having their tech and allies for the rat ogres and warp throwers and machines. But no, betrayal, alliance units suddenly gone, and ambush swarmed. We were just 4 turns away from sacking Reikland too.

Next time I'm just keeping vampire alliances between vampires. Coast, lend me your Bullets and cannons. We drink rat blood tonight!