[Ranylyn]

Take a look at this screenshot for a second.



Is getting knocked down supposed to not interrupt it's big "OH SHI-" attack? it takes a turn to charge it up so I thought it might be like an Invocation. Alternatively, it's entirely possible you simply need to imnterrupt it by doing enough damage since it starts at Lv 100 and depletes as it takes damage, but as you can clearly see by the FP it has consumed, it's pretty unlikely that you'll be doing a whole lot of damage to it unless you go at high levels, rendering it impossible to break the attack at appropriate level ranges. (For the record, this battle took over 80 rounds at level 25 with all 3 mercs and a character who could not even damage the Guardian once Demon Translation happened struggling desperately to keep them all healed so they could keep doing their 4-8 damage each if they hit. And yes, the Guardian ran out of FP and kept summoning Ravens/ Using this since they cost 0 FP apparently.)

[Neus]

Yes, you have to break the shield in order to stop the attack.