Holy crap 66 pages, mangaka's spoiling us.
I really loved these chapters in the LN, seeing Shuna finally pop off and let off some steam was great and Rimuru calling Clayman out on his BS was cathartic as hell.
I also love the notion of Shuna using Holy magic (a magic that monsters aren't normally supposed to be able to use).
It's able to shake up the faith of members of the Holy Church without fundamentally changing anything about it (all Holy magic requires to be able to used is strong, unwavering faith in an object or being), it's a fantastic way to flip their way of thinking and prejudice against monsters.
Also, about Shuna's Unique skill, all it actually does is combine and separate magic she already knows, she can't just make it out of nothing, the thing that makes it strong for her is that she has VAST knowledge on different kinds of magic (which grew even more after Seeing Rimuru synthesize magic in a similar way (like with the teleportation magic mentioned earlier)).