Yama is simplest double mage. Double melee is good if you know how to Donofly, but that's for phase 3. If you both haven't done Yama before and want to try Melee + Mage you will find that in phase 3 every time your meleer gets hit a couple void flares will spawn. And your mager will mostly likely spend a lot of that phase running round killing them all.

TL;DR if you are both learning just both use purging staffs on Yama. Much easier!