If you pressure Seris into using her escape, turn around and listen for Seris uncloaking. Try getting someone low in the mean time, this will often cause Seris to believe she is safe since you aren't looking at her and will uncloak to heal her team.
Your shadow travel can make you immune to everything. Use it to cancel ultimates and abilities, or use it in sticky situations. (I recommend using veil since it can make you go into shadow travel faster.)
Just because you're behind cover, don't think your safe after fighting a Seris becuase rend soul can end you if you're low enough or just make you more vulnerable to any other unless she already used it.