If you're playing as a melee-centric character, go for broke with your physical attacks, keeping a careful eye on your health. The idea in attacking this enemy is to be aggressive yourself, but in an intelligent sort of way. Though the Ogre seems to be a daunting, aggressive enemy, the fact that you have Alistair, the Circle Mage and your trusty hound with you should even the field of play considerably.
A gigantic enemy known as an Ogre occupies this top floor, and to get to the signal that you have to turn on for the soldiers fighting the Darkspawn in the fields below, you'll first have to fell this foe. This floor is by far the smallest of the four floors that make up the tower, and as soon as you arrive, you'll be greeted with a rather scary cutscene. There's no map for the fourth floor of the dungeon in this guide because, well, you won't really have much of a chance to use it (or much of a need to use it, either). Saving Ostagar | The Tower of Ishal (Conquer, IV)