i have no idea, but im sure a few shots from railheads will sort him out
Come on, none of that
Every damned thread it's "Tau: Shoot it with railguns"
'Sides, what with being an IC, actually shooting him at all is going to be all but impossible. That's one reason why I went with a character...shooting him to death usually isn't an option.
Myself, I would fight fire with fire. I'll take their super-psyker down with my own super-psyker. Mephiston has an LD 10 hood to cock-block any attempt he makes at using his numerous fancy powers, meanwhile if you're daring, he's got a better chance of surviving those bloody runes of anyone. T5 and FNP means perils of the warp are annoying but not as threatening as they are for anyone else. Meanwhile, except maybe his wings, he doesn't need a lot of psychic tests to be insanely lethal and effective. Even without using his Force Weapon, he's got some wicked combat capability...granted, that 3+ invul save is a pain in the ass, but chances are Mephy can dish out the volume of attacks needed to cut him down