you need lv 5+ to do it. Best to start with 3 electric auras at each choke point hallway ending away from the crystal. Then place an ensnare aura on each electric aura. Once you've done that place an electric aura on each of the hallways leading towards the choke points. After that, place if possible a healing aura near the crystal.once you've done that place 2 electric auras by each spawn point t'pol give extra protection. although, make sure your monk has good dps and ranged damage for the ogre.