Have two people up the front behind that pillar in the middle on the stage shooting at the ogre. Have two on either side of the field behind the walls and the rest behind the rocks at the back. The two at the back will help when ogres go for the rest. Shoot the eyes and it'll give you bonus damage and yes these do stack. Take down the ogre but save your super because you'll need it for the wizard. Once the ogre is down run up onto the stage and use your heavy, super, everything you have because once the ogre goes down you only have so much time to kill the wizard before another spawns. Any questions just feel free to ask