For this purpose, Shale is an excellent choice. With Large Natural Crystals Shale has extra resistance against the Broodmother's spit attack. Also use Stone Roar as frequently as the cooldown will allow to keep the big monster's attention on Shale and away from your other ranged attackers.If you have Shale in your party and another member capable of acting as tank (Alistair, The Warden), an alternative is to use Shale's Stone Aura ability (best if Shale has all aura talents including Supernatural Resilience) to provide an excellent party buff. Shale's aura will reach all parts of the Broodmother's main chamber. All other party members can focus on damaging the tentacles, darkspawn, and the Broodmother herself, though Shale will need the occasional heal thrown her way. Shale's aura is also effectve if the party has a mage but is low on lyrium potions.Rock Barrage - the rocks will all hit and trigger physical resistance checks due to Broodmother's enormous hitboxIf you do not have Shale, it easy to have all your party but the tank do ranged attacks on the broodmother and let the tank keep the darkspawn. If you have 2 or more tankers have them rush the broodmother while the others do ranged attacksEquipment RecommendationEditBeing a darkspawn, the Broodmother has a weaker Fire resistance. Use weapons with fire damage or runes. Outfit tanks with massive armor. Equip archers with fire arrows if you don't mind using the ammo. Items with nature resistance are particularly useful, especially for tanks, as the Broodmother deals hefty nature damage.It is possible that any item with the buff "Weakens nearby Darkspawn" will affect the Broodmother. (Needs Confirmation) See: Dragon Age: Origins