I suspect a lot of Ronda 60's will start appearing soon in lower tiers. Very soon actually. Quite brilliant that they included a XP barrel in this dungeons divers event as last reward. You get Ronda, farm her masteries from 5-1 to 5-50, rank her up, use the XP barrel. there you go, a brand new maxed out 60.
More advanced players might choose to use this XP barrel on a more powerful champion they've recently pulled, but for new players, this should be the strategy to use (on Ronda) to quickly gain an edge in their arena tier.