Are you really going to be using Zuriel staff whenever you mage? That sounds highly impractical. 490 vs 465, roughly. 35 lp extra damage is worth it. I use Miasmic Barrage almost everytime I fight people. The staff is very cheap for how powerful it is. You're spending 10448gp a minute when using Zuriel's staff and since it doesn't take any longer than 2 minutes to kill a meleer if you're a mage I'd say it's very much worth it. And if you're barraging rock lobsters I'd highly recommend a SoL and battle robes anyway... Oh, and Ice Barrage maxes at 471, not 465 :P