To beat the ogre on level 10, You need units, to go close to it so the ogre swings its axe, after the ogre finish its attack it takes off its helment thats when you start shooting at it, Keep doing this after you kill it, if you run out of units use your hero and keep a distance from it when you see it raise its axe run back so it doesn't hit you. Note: bomb arrow knocks the ogre down.