For staff's passive skills I'm using Asceticism, Mana Amp, Flame Condensation, Frost Master, Forbidden Sanctuary and for dagger's passive skills are Assasin's Step, Vicious Fangs and Wrathful Edge. For my build I only focusing on Dex / Wisdom to increase my max damage as much as possible
I think the best combo is Staff/Longbow because both of them are long range weapon it will have a lot of damage out put from 1 player but if you want a higher damage for meteor/lightning skills staff/dagger is the best
Just cloak first so I can cast meteor without them noticing me then use infernal meteor -> ice spear and the rest lightning skills ( sry for late reply 😢 )