@RevanCrusherKR23 Use Leliana to fire at the Archdemon with specialty arrows/bolts, if you have them. The nature ones work best. If she has the Ranger specialization, summon a pet to help keep the Darkspawn back or the Archdemon's attention. Wynne would work best playing defense, since you're a mage yourself. Stock up on lyrium potions extensively and set her tactics to mostly heal and support allies. (Haste is great, if you have it, while Cleansing Aura is a must.) Any major offensive spells she uses should be controlled and directed by your personal command. Alistair should be taking on the Archdemon as much as possible, occasionally firing his Holy Smite attacks down if he can. For the army, the mages work best in the beginning to lower the Archdemon's health rather quickly, though they really don't last long once the Darkspawn come out. If you chose the Templars, they'll work just as well. Use the Dalish once the Archdemon goes up to the spot where you can't attack in melee, if you sided with them. Otherwise, it's up to your party to strike it from afar. Using your spells, all the arrows/bolts you can put in it, and Alistair's occasional Holy Smite when it recharges, you may not need to use any of the ballista. The rest of your melee-based army is meant more for holding back the horde while you take on the dragon-god. The one ballista can be the best place to gather, if you put your fighters just right to block anyone coming in. Only be aware of the AOE attacks by the Archdemon, though Wynne should be able to fight against those.