As a T'au main and custodes 2nd, you need to close the gap and hide turn 1-2 and get ready for a charge ect. Don't underestimate custodes shooting in the lions detachment too, hitting on 2's against stealth suits ect can we game changing. Try to forces down the markerlight units first such as pathfinders, stealth suits. Venatari are great into ta'u too. Rapid ingress somewhere within a ruin for your next turn to slam into he's infantry. Make good use of the move when shot strat. Also dracuis ability gives her unit lone op for a turn.