There are 2 practical skills to kill a Banshee in Runescape
Will use in phase4, a hatred spirit will be transferred to a corner, you have 15 seconds to kill, if failed to kill success, then the next 15 seconds apart from QBD and casting of hatred spirit cannot conduct any activities, cooperate with fire very deadly waves. Only 1600 HP but hatred spirit, 1 ~ 2 can be struck. And you can pick up the much Runescape Gold which Banshee drop.
Phase 3, 4, QBD per second to the court in addition to the demons (exception) of preparation time enchantment dealing 100 damage and reply their 200 points until the demons die, this need you kill as soon as possible, AOE skill would help.