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.
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.
Fernando's ultimate leaves him CC Immune, but not his allies; If he's using it to save someone from being finished, knock them off his ult area (preferably towards your team) and secure the kill.
Don't engage right away, see if there's a portal near him. If so, knock him away from it to prevent fleeing and healing. If your ult is up, stun him to prevent another portal and to protect yourself from Broadside.