It It might be a little early but the last episode of re-zero was amazing and also give us insight on what could be the final episode of the season. Now that the tower is almost completely finished. We see the final boss with the shape of a Divine Dragon called Volcánica. We can predict that the final showdown will be happening between a media and this Dragon as well as subar and the mabbyst at the bottom of a tower.
I think the key of breaking the tests of the tower will accomplish the conquest and recovery of everyone's memories and maybe the resurrection of Meli, and Shaula. But I wouldn't hold my breath..
The fight between REM and the Glotony brother was pretty amazing, a bit remenizing of Dragon Ball fighting art style, with them going all around the stairs of that huge hole inside the tower.
So one of the theories out there is that Amelia, she jumps the Divine Dragon. She will unlock some kind of secret on that wall where there was a bunch of hands in print in it. My guess is that it was Subaru's previous reincarnation similar to the way that Shaula remember Subaru as the builder of the tower.
One thing that keeps me a bit nervous is how separated is the group as Emilia is on the top. Ram and Rem are inside the tower and Subaru is fighting outside of the tower. The finale still up in the air as what would be the conclusion, but it does feel like this is the final battle of the arc.