If you're going to be playing a deck like that for a while, do NOT upgrade the Firefly Queens. They will make Elite Fireflies, which produce FIRE Quantum, so your Rustlers would be useless. If you're serious about playing that deck, then upgrade your pillars first, though if you're farming PvP, AI3, and T50 for money, it'll take forever, but after the pillars are all upgraded, next would be your Rustlers, then the Owl's Eye, Empathic Bonds, and finally the Druidic Staff. Hope that helps.