Why don't you understand about Storm of Armadyl? I always use it at DKs, so maybe I can help you. Edit: here is some information about Storm of Armadyl (SoA): Ice Barrage has a max hit of 490 with a chaotic staff. At 100% accuracy, that's an average hit of 245. Since you can cast one Ice Barrage every three seconds, you will deal 81,66 DPS on average. Storm of Armadyl has a minimum hit of 227 and a max hit of 478 with an Armadyl battlestaff. That's an average hit of 352 at 100% accuracy. You can cast one SoA spell every 2,4 seconds. This means it does 146,66 DPS. Dagannoth Rex has 2,550 LP. It takes 10/11 casts to kill him with Ice Barrage. It takes 7/8 casts to kill him with Storm of Armadyl. As for price comparisions: one Armadyl rune costs 1,700 gp on the GE. Ice Barrage costs 1,278 gp per cast. This means you spend 12,780 gp on average per Rex kill with Ice Barrage, and 11,900 gp per kill with Storm of Armadyl. So not only do you kill Rex a lot faster with SoA, it's also cheaper. You get more Rex kills per hour, which means more profit as well :)