Never tried it. I figured you could juggle the relics. But forgot that would take too long and a praetorian would have closed the gate by then.

Nope, if you open the portal and full fledged sprint to grab relic and jet it out before the Praetorian gets to the plate, you're fine. Then you have to go just as fast (if not faster, due to the center conflux) on the right side. You just juggle the two until you get to center. I counted to 5 before I switched relics. You've just got to spam the supercharge and the mini ground-pounds. So, while nearly impossible, it can be done. I've done it before.