So, finished watching Frieren episode 26 - The Height of Magic
A bit tricky to sum up chronologically, as the overarching event is Frieren and Fern fighting Frierens replica with a lot of other simultaneous events happening. The group decides on strategy... Fern and Frieren are the only ones with a chance of surviving against Frierens replica. The rest spread out and engage the other replicas which are slowly but steadily congregating on the room outside the "boss room".
We get a bit of background on Ubel, which comes across as a psychopath. Failed her previous exam because she killed the proctor. Her magic is slightly different because in this world, it's' all about logic and visualization. If you can visualize it and it makes sense, a magic user can make it happen. Ubel doesn't need for it to make sense. She just has to believe it will succeed (and being slightly unhinged, her ideas of what is possible and not is slightly off kilter). Her specialty is attacks that cuts through anything.
Methode has located most of the current replicas and Denken and Methode find some of the stragglers, explaining what is going on.
Mage battles are a bit like rock, paper, scissor, so they attempt to find their replicas weakest match up. Sometimes you succeed...
and sometimes you don't. They also discover that the replicas come back. Their demises being temporary...
Frieren starts fighting Frieren to give Fern an opening for a bit of sneaky backstabbing...
But, the replica, weakness or not, is simply too strong for Ferns friendly tap on the shoulder...
Plan B... if plan A doesn't work is for Fern to face Frieren head on (and not mentioned explicitly, but assumed) and stay alive for more than 5 seconds...
Fern uses the A10 tankbuster gun version of magic, firing 6000 magic missiles per minute at replica Frieren
Fern: Look you stupid bastard, You've got no arms left.
Replica Frieren: Yes I have.
Fern: Look!
Replica Frieren: Just a flesh wound... ZZZAP!!!
Fern succeeds in her primary objective though, she got replica Frierens undivided attention
But, Fern having all of replica Frierens attention gives Frieren the opening she needs, allowing her to cast a spell which annihilates the replica in a display of blue pyrotechnics (a mage version of a tactical nuke?)
Time to kill the monster behind the replicas (which also makes all the other replicas turn to dust)
Aftermath:
...and now off to the third test
Edit: I'm guessing Frierens reference to 80 years ago is when her party fought the demon king, being the last time she fought completely without restraint and using martial spells unknown to human mages
Edit2: Somebody made a 3 minute video, covering 3 of my pictures, having edited together just the scenes with Frieren fighting her replica. I'll leave the pictures in case the video gets taken down by Youtube