Tactics?!
If you haven't notice my whole army is capable of moving very fast which will be great for this mission. Basically my men will form a big block of tanks with one raptor squad and my lord in the middle of them, shielded by their tankness. Using the terrain to keep obscured from the Tau.
Meanwhile the other Raptors (The ones with melta and plasma guns) and the Termies deepstrike behind the Tau, pretty much within their deployment zone. If they aren't already close to the Tau then they'll move there next turn and force Romulas to split his fire between my rhino battalion, papa nurgle, and the flies at his back. Plus they'll give him a nice dose of plasma/melta heat before assaulting the closest thing if they aren't blown to hell...but even if they are I don't care They're a distraction for my main force.
Now the Predators and Vindicator will head straight for Papa nurgle and unleash on him with the demolisher Cannon and a bunch o' autocannon and heavy bolter shots the main target would be the bikers after that the havoc Rhino then the plague marine rhinos. After that they will sit and blast away at him moving back every once and a while to keep out of melta range
The three normal marine squads and their Rhinos will go straight for the objective and tank shock anything thats inside and shoot 'em up with their havoc launchers and if I'm going slow enough some of the marines inside. Once they are safely inside the Rhinos make a triangle of metallic cover and the one or two squads get out in the safe zone created.
Meanwhile the lord and his Raptors go for the front/side or what ever is presented of the Tau formation, traveling behind the noise Marine Rhino. The Noise Marines either dismount and fire their sonic blasters in heavy mode and the blastmaster to pin anything around them or they ride it out and assault.
The lord's squad are combat monsters. Blessgiver will tear Typhus to pieces if he decides to show up any where near my lordy.
Remember I have lots of guns to hurt things with...even things with high armor saves and/or feel no pain. The plasma guns should help too and heavy bolters.
Wow that was long winded and probably stupid...
30 Raptors.
30 marines.
10 Noise Marines
3 Terminators
2 Predators
1 Vindicator