If you had to iceblock in a duel and the enemy is very low, the fastest action you can do coming out of iceblock is actually to primary fire, almost all the other abilities have a slight delay. You might die, but you might not, and they WILL die.
Avoid long duels vs Buck. Charge and burst him down or run. Fight Buck with a pillar or an obstacle between you and him and you will lose if he gets out of cauterize to heal up again.
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.
Crowd control reduction or immunity is critical against Atlas, especially if you are a tank or support. This will make you less vulnerable to his Rewind effect, and reduce the time you are trapped by his ultimate.