When she has her dragon, you can use your ultimate to execute him if he is below 65% health, so try to save your ultimate when u know imani also has her ultimate up.

If playing Stunning Visage, when you stun Viktor he has his head up, so try to headshot your shots when he is stunned and an extra 600 dmg after going through him are enough to kill him.

If you are playing Stunning Visage, wait for her shield to come up then stun her, which completely shuts down her shield. Then, she is an easy target to burst down.

It is crucial to avoid her obliteration damage, as she is immune while doing it, deals plenty of damage and will even heal her if she has saved darkness stacks.