Hmmm. Tau. First thing that strikes me as a big no no is deploying only the single venom. Tau have no problem taking out a single venom certainly at that level!
How is the grotesque formation getting into battle? Footslogging them is not advisable as Tau have as standard strength 5 weapons that toughness 5 offers no protection.
Blasters and dark lances are our beat defense against tau battlesuits because we can insta kill them, that is the trick! Think along those lines if your mate plays battlesuits!
I would maybe drop the blasters on the reavers though as they will be jinking most of the time/when Tau allow it, and the points could be used elsewhere perhaps. In the spirit of saving points I would be tempted by dropping Urien in exchange for a regular haemocules perhaps and use the spare points to get some transports for them!
Delicious and Coven-Baked for your Pleasure
A very slow, 30K Salamander Distraction Log: VULKAN LIVES