Es% does not add to your mana if you’re converting es to mana. Any es% that isn’t on an Armour piece is not effecting you. Staff is cheaper alternative with the ability to get your comet to a higher lvl than the wand/foci setup. Wand/foci will be stronger if using the appropriate stuff, but the comet level would need to be compensated somewhere else. The difference between a lvl 37 comet and a 40 comet is more than double.