Your best bet is to stay back and try to farm darkness off of her shield. due to the fact that trying to hit below her shield will be near impossible due to your projectile size.
Evie's ultimate slows and cripples enemies, soar towards the enemy's spawn and try to catch their tanks and healers in the Ice Storm, it can seriously delay them and give your team precious seconds to secure the objective!
Vora struggles to out dps Io's healing if she runs Life Link and/or restored faith, and is hiding around Luna which may allow Io or her team a time to kill you, to counter this attacking Io when Luna isn't around or killing Luna will work.