Due to what seemed like a good response to my guide for one of Vilanciel's EX dungeons, here's a battle guide for the other EX dungeon fighting against the Divine Wolf

Link to Divine Beast's Prison battle guide for reference

Merciful Glory battle guide

(As with my guide for the Divine Beast's Prison, Vilanciel's other EX dungeon, unit and weapon advisory is subjective)

Ok, so the battle against the Mystical Wolf and Balamgram are actually very similar to each other in the way the battle and attacks the boss uses during it.

Like Balamgram in the Divine Beast's Prison, the Mystical Wolf inflicts Status Ailments, with a very high chance to inflict Sickness with every attack and with it's threshold attack inflicting Paralysis.

As with Balamgram (and vise versa) every 5 turns guard all of your units, but instead of an attack that reduces your units HP to 1, it buffwipes you and will still attack a couple times after the wipe.

At ~75%, the Mystical Wolf will charge an attack and say "The Mystical Wolf Is Opening It's Mouth Wide" and proceed to use (I think it's it, I don't remember) "Mystical Wolf's Howl" or "Sacred Howl" and it has a very high chance to paralyze your units, the same happens at ~25% instead of ~40% like Balamgram.

Every once in a while (I can't say when) he will buff himself with an attack buff, his attacks can hurt quite a bit, but the attack buff makes them hurt quite a tad more than they already do.

He also has fairly powerful (it can kill your units quite easily, even if their Thunder) Single Target and AOE attacks

Now for units

As opposed to Burning Soul Balamgram in the other Vilanciel EX, the Mystical Wolf is has the Water element, so Thunder is the advised thing to use. The absolute best (most likely) units to use here are a 5* Pamela and Kanon/Washing Machine (Reddrag). Pamela has two defense buffs in a base just straight up defense boost at 80%, and a 40% Atk -> Def buff as well as a 25% boost to BC/HC drop rate.

Kanon and Reddrag are very powerful in what they do as well, as it's almost required to actually defeat the boss. Unlike the other, Kanon has a 10 hit BB that nullifies and removes status ailments, while Reddrag has a 1 hit BB that does the same thing, but negates Atk/Def/Rec down effects for 1 turn (so it's pretty negligible). But both negate and remove ailments so it's a very powerful buff against Sickness (which reduces your units Recovery stat) and the Paralysis it inflicts.

Now for the weapons, LS spheres, and element level

Like with Balamgram, the Twin Pistols (best at lvl 10 minimum) and the Brave Spear (minimum lvl 15, lvl 20 recommend) are the best weapons to use. As against single enemies, BC drop rate can be pretty abysmal, so Pamela's BC/HC drop buff paired with the Pistols BC Efficacy boost greatly benefit each other. The HoT from the Brave Spear (lvl 15 weapon skill, or lvl 20 SBB) with Negation from Sickness (given from Kanon or Reddrag) greatly increases your units survivability overall.

The best LS spheres to use are (similar, again, to Balamgram) are the Shining Stone, Noble Blood Gem, and Lupine Mantle (though that'd most likely be your friend unit's LS Sphere). The Noble Blood Gem is generally better (it's 5% more HP/Rec than the Shining Stone) as it has more effects than the Shining Stone, while the Lupine Mantle greatly increases your ability to survive as it's 25% all stats.

Your element level should (at minimum) be level 9 so your 5* units get 80% of their stats and 65% BB gauge fill rate.

Hopefully this guide helped

                                       -W00DS