from what it looks like, the entire combat system seems to have changed.
I think guard might now give HP to said gauge and work as a pseudo hp.
Based on what we see, i think: (Havent played CCC yet so excuse any lack of info for if any of this was in CCC. Any names i got from a translation here) The attack system looks similar to/reminds me the command card system from FGO but with Break, Guard and Attack. Guard acts as Pseudo HP. Break deals a lot of damage (maybe going through guard to a degree) and not much to HP while regular attacks only hit guard.
We can also see an "AP" system for moves Based on the images, "Slash" is 1 and what i assume is a Guard is 3.
I also see a "Damage Boost" for 0 AP The last thing i see "The Burning Fountain of the holy one" (2AP) seems to be a skill with a description of "3 damage x 3 times" "Only the number of successful attacks" "1 attack"
I also see a "Guard" with a description of "5 get the guard" (Machine translated so likely not accurate but idea is same) with 1 AP usage so attacks could have different skill values (EG Attack with 2AP could deal 10dmg while 1AP attack could deal 5)
If this is the case i would guess the old system of enemies having patterns might have changed.