User blog comment:KKytes/Third Arc for Newbies: A Simple Guide by a Simple Summoner/@comment-30373133-20170910133952/@comment-30054866-20170911124818

If I had to give a minimum Summoner Level, it would be around the 40s and above, but do note that level isn't incredibly important in this situation.

IMO, even if leveling the Summoner and boosting its parameters as a result is important, considering how squishy the Summoner unit is with only two of the 19 weapons unlocked, these two don't really matter much. What's much more important is:

A) Summoning Arts;

B) Buffs to bring;

C) The Spheres you have equipped; and

D) Your friend lead.

Firstly, the unit you bring, including the Summoner Art related to it. The unit you bring is integral, as it is the only unit who can bring valuable buffs such as Mitigation and health management. However, the strength of this unit both parameter and buff wise depends wholely on its element's Summoning Arts. As such, I would suggest to grind the corresponding Summoning Art to about Level 18, as at that point you unlock 70% of the BB gauge boosts and 80% of the parameter boosts for said unit, assuming it's a 5* unit. In terms of buffs to bring.

Considering this is against Duel-SGX, I would suggest the buffs you pack be more management oriented over defensive buffs, although both are important. Ailment cleanse/null, Burst heal, and HoT, in particular, are buffs you should focus on. Aside from this, BB management buffs, especially BC fill when hit, do help. Lastly, defensive buffs such as standard Mitigation and defense up buffs, as well as Critical Null and Elemental Weakness Null help.

Spheres to equip should include BC on Hit buffs, Ailment Negation, HP Oriented (i.e. HP when hit), and Crit Null are those you should prioritize. Leader Skill Sphere wise, since you're starting out, try grinding for any defensive spheres, such as Guarding Light from Bectas or Ogre Gauntlets from Vilanciel, which you should've unlocked the moment you finished Bectas. Your friend lead, if possible, should include parameter boosts, BB management buffs, and health buffs. Lupine Mantle, Armored Soul, Automated Warrior, Akbutecca Crown (and everything within it, i.e. Warding Scepter, Myrmidon Helm, etc), and so on and so forth.

Lastly, your friend lead. Your friend would be the one who would, hopefully, bring the most buffs. The Crystal Staff, Yearning Scythe, Great Sword, Sacred Lance, and Radiant Longsword, in particular, are weapons which bring valuable buffs which can help a ton in the battle against this robot. If you want to clear this quickly, you could pack a nuking weapon as well, such as the Bow, Dancing Blades (gives normal attack boosts), Savage Whip, Thundering Maul, and such.

Just a sidenote that I'd wish to add: You don't need to clear this EX dungeon just yet. It's easier to stick to the starting weapons for now and keep grinding through Vilanciel, the next area, until you get a good weapon or an extra Summoning Pedestal, or to get a better sphere.

I'm sorry if this guide was a bit all over the place >.<

I at least hope I helped shed some light into the situation, somewhat! (ovo)/

If you have anything else in need, do ask. (^^)/