What determines how quickly Mercy's ultimate charges?

Solution 1:

Mercy charges her ultimate in the following way:

  • Passively charges 1% per 2 seconds
  • 1% per 10 damage done with pistol or melee
  • 1% per 12.5 damage healed (self-inflicted damage such as S:76's or Pharah's rockets do not charge your ult)
  • 1% per 15 damage done by amped ally (Mercy's damage-boosting blue beam)

The fastest way to charge your ult, therefore, is to avoid sticking to one ally unless they're dealing consistent damage. As soon as someone is topped off, either find another ally or begin damage-boosting.