The CPUs going all out against the big blue artillery robots.
IF and Nepgear riding on a bike with IF shooting down a big robot that flies off towards them.
Uni protecting Rom's and Ram's blind spot by sniping enemies from the shadows.
And gunning down robots while sliding down a hill. As well as going toe-to-toe with another after being surprised by one before having a chance to reload.
Nepgear's transformation at the end. That is all.
The way she was able to transform was by finally gaining the confidence to step out of her sister's shadow, something fans have been waiting for for some time.
Much of the episode counts (When it's not being heartwarming). The battle itself is fairly awesome, with Rom and Ram transforming together in order to protect Nepgear, and Uni soon after without even noticing it (for reasons similar to Nepgear above). Arfoire herself is no slouch, easily curb stomping the girls, even with their transformations. In the end, it takes the sisters Share energy and the CPU's remaining energy (Both CMOA's on their own) to stop her.
Special mention, again, goes to Uni for being the only character to score a successful hit on Arfoire (specifically, her wings) while untransformed, something Nepgear, Rom and Ram were completely unable to achieve without accessing HDD.
To round it off, she scores three successful strikes on Arfoire, the highest of all the Candidates. All of which targeted her wings. And let's not even start on the difficulties involved in trying to shoot down an object moving unpredictably at high speeds...
The biggest bomb dropped at the end of the episode: Peashyis in.