I made a mistake on my DPS choice, so this fight took me longer than I wanted, but it did help me have a realization when it comes to tanking that I thought I would share because it goes against the normal convention. Normally you would pair a magic tank with a provoke tank, and wouldn't want a physical cover tank because of the competing covers. However, this fight is quite easy when using a physical AOE cover AND a magic AOE cover if you bring physical DPS. Allow me to explain.

Materia keeper uses a physical counter when hit with physical attacks, and a magic counter when hit with magic damage. This attack cannot be provoked, but it can be covered. I used an evasion Basch and Chow. Using the AOE cover of both, when my physical chainers attacked, Basch covered the counter attack and took no damage. Since that was still considered my turn for the cover, when the boss used its magic attacks on its turn, Chow was no longer considered covered and blocked the magic damage no problem. This gave me a huge safety net and even though it took me a while because of the elemental imbue and resistance, I was never in any danger of dying. My Basch also has Golem and Moogle Plushie, so on the second turn I still provoked like normal, though I don't know if that had any useful effect on the fight. WoL should be able to handle it no problem as well.

TL,DR: This is a rare case when physical and magic AOE cover can both proc without interfering with each other.