It's not that challenging of a fight if you have a good squad. Essentially it's a large boss surrounded by 3 minions. Chaining together 3-4 AoE attacks wipes out the minions pretty consistently, especially if you bring along a good friend unit.
And then you can concentrate on the big bad boss. As long as you get it down to 50% in the first round, he wastes a round focusing his power and you can finish him off in the second round with single target attacks before he even has a chance to unleash any damage.
I'm running it with Chiz, Lightning, Firion and a friend for the AoE onslaught, Refia for embolden, and CoD for barrage/wipe up.
Where you can run into trouble is if the snowman attacks. He unleashes a whole slew of -aga spells including death, and he can easily wipe out a party if you're not careful. I always wait with CoD to make sure I can get him under the 50% mark in the first round. If I can't, I push out her omniveil and that usually protects my group enough to survive.
That's been my strategy.