Ana's Nano Boost is her Ultimate ability. When used, a nearby character of your choice gets a significant damage, speed and defence boost for 8 seconds. During those 8 seconds, you need to get 4 Eliminations or Kill Assists in order to unlock this Achievement.
It is possible to get this through natural play even if you are not part of a group, but you need to be aware of a few things first:
> Combining your Ultimate with another character's Ultimate can be effective.
> Your Ultimate will charge fairly quickly if you focus on healing your allies. Grouping up with a Tank speeds up the process further.
> Good Heroes to boost include Soldier: 76, D.Va, Bastion and Roadhog, though any Hero that can quickly deal damage to a large number of enemies will suffice.
> It is easier to unlock this Achievement in areas where the enemy is grouped up tightly. Playing on Defence on any map with a payload is a good start, the final points on Numbani and King's Row cause the attacking team to bunch up quite easily.
>
Communication is important when using Ana's Nano Boost. Use the emote wheel
to inform your team that your Ultimate is ready
. If a teammate acknowledges then use the Group Up command
to let them know where you are.
> After you have used Nano Boost, keep firing at the enemy. Your Eliminations will also count towards the Achievement's requirements.
As always, this Achievement can be made easier by grouping up with friends or joining a boosting session, but if you cannot do either then there is still a chance to unlock it through natural play.
Good luck.