How to beat Undead Grius in Metaphor ReFantazio
Once an ally, now the enemy...
Defeating Undead Grius in Metaphor: ReFantazio is something you need to do when you first set foot in Regalith Grand Cathedral.
During this Metaphor: ReFantazio fight our Archetypes were Seeker (protagonist), Warrior (Strohl), and Knight (Hulkenberg). At the very beginning of this fight you'll also unlock Synthesis skills which will come in handy while controlling your party mid-battle. The fight with Grius is one single phase fight but it doesn't by any means make it an easy one - in life he was a skilled warrior so in death he's a brutal skilled warrior.
With that in mind, here's how to beat Undead Grius in Metaphor: ReFantazio, but keep in mind this has been written for the 'Normal' difficulty and the battle may be different if you've chosen a higher level.
How to beat Undead Grius in Metaphor ReFantazio
To beat Undead Grius in Metaphor ReFantazio you need to use your Archetype skills and newly discovered Synthesis skills to chip away at his health as well as keep your party alive during his enslaught of attacks.
Throughout the battle, Grius really only ever uses two attacks - the Phantom Dance one that impacts the entire team and a sword attack directed at a single party member. You can guard against them if you choose to do so before his turn, otherwise you can't do much about the attacks except survive them.
If you've got Hulkenberg's 'Jump Thrust' Synthesis skill then use this to lower Grius' defence for three turns as well as deal some piercing damage to him. If you lower his defence you've given your party a better chance at damaging him with their attacks. We used this every time Grius' defence would replenish itself.
Also, use your new Synthesis skills to inflict damage but be careful with how much you use them as they take MP from any members involved and also will use up the turn of the action owner as well as the ally they're combining with. This can mean in exchange for dealing a damaging blow, you give Grius another opportunity to strike - we found it best to use these skills when Grius' defence has been lowered.
One of the most crucial things to remember about this whole fight is to keep your entire party alive - if one member gets low health then you need to replenish it enough to keep them in the fight. It'll be much harder if one ally dies and there are two, or even just one of you left.
The Protagonist's 'Cyc' Archetype attack does inflict a decent amount of damage on Grius too, which is good to know as Hulkenberg's Synthesis skill uses her and Strohl's MP, leaving the Protagonist's one free for this. However, don't forget that basic melee attacks between the larger ones will also be of use to you - don't just focus on special moves.
If you follow all of the tips above and keep persisting with the battle, you should be able to defeat Undead Grius rather quickly.
That's it for now, we hope you enjoy Metaphor: ReFantazio!