Rescue Beam’s pull is fastest at the start of the pull, after which it decelerates. The further away you are from the puller, the faster you go. At any time during Rescue Beam, you are able to cancel and return to normal.

You can take advantage of the large amounts of speed to slingshot allies across the map by cancelling Rescue Beam just as you start pulling them towards yourself.

The best conditions are for the puller to be as far away as possible, for the puller to immediately cancel once the target starts getting pulled, and for the puller to have some sort of leverage over the target (typically though standing on a higher platform).

To execute, cast Rescue Beam onto an ally. Start pulling, then immediately cancel. They should be slingshotted behind you.