Terminus's axe can cleave through your shield and will hit your ultimate drones, and his Shatterfall will make it hard to run. Keep at a distance from him at all times if possible.
Yagorath's Caustic Spray deals damage in an area, and will hit your ult drones if she shoots at you. Try to stay out of range or out of sight so it's harder for her to target you.
Vivian has some of the highest sustained DPS in the game, especially with her ult active. If an ally gets hit by Yag's ult, you'll easily be able to shred through her ultimate health to save them.
Assuming you don't have more important targets, hold your ult for when Vivian uses hers. Tag her with a bit of damage, then ult. Be wary of supports being nearby, or if she's running the Scapegoat card, as either will likely shut down the kill