Easy way to kill a fernando is to get behind the enemy and hit him from the back which will force him to turn around leaving him vulnerable to champions that were in front of him before,but you will have to be careful of his allies.
Immortal will make Fernando invincible, even to Dragon Punch. If he's hit, Drogoz will put Fernando down to 1500 health, and Dragon Punch will be cancelled.
If playing against a Viktor, or any other hitscan champion, try flanking them, because they will have a longer time to react to the damage, and you can unload about two shots before they will detect you and start firing.