Posted By yakface on 09/16/2007 4:13 AM
I'm also big about keeping my team games fit into the fiction, so I get your pain.
If you absolutely *must* have these two armies pair up with each other I'd suggest the Necron player should have to take 'the Deciever' in his army. The Deciever can trick anyone into doing just about anything for him so it isn't too much of a strech to envision some cunning plan involving using Tau to eradicate the Imperial presence on a planet.
Now thats some rationalization I could agree with easily as an opponent.