Orbs are easy, just use a gun and subclass matching the type on your armour quest, it's different for all 3 classes read the armour description. I did titan today, it was arc, so I used striker and risk runner, took 1 run of eaz. 5 mini bosses also easy. Equip a sword and rally a flag before you go to the eaz, rush to the first boss, 1 done, then look for markers on the map, don't worry about dying so jump in and sword. Assists count so if you feel you can't, just follow another player and get damage on the bosses.

what are the exact requirements? miniboss should be easy, they are highlighted on your radar. the orbs might need to be a particular type (solar, arc, void).