Now here’s a question: what’s best to field in the arena? If you are going to field anything in an arena, it should be the highest level possible. But here’s a hint: it’s best to use armors with high Defensive values or Defensvie values very close to those of the offensive values. I’ve noticed that it’s always better to absorb more hits than trying to get more damage in. This has to do with how often your soldiers miss and how little extra damage the high attack suits really do.
As far as what elements to field in the arena, there’s two school of thought to this.
The “Paired Elements” method: If you use “paired elements”, you’re using suits of armor that are “connected” elements. The suits that fit this mode are Air/Earth, Air/Water, Water/Fire, Fire/Magic, Magic/Earth. The advantage here is that you minimize the chances of a vulnerable hit from opposing armors. The disadvantage is that you also minimize the chances of getting a vulnerable strike.
One thing I’d like to point out here is that if the opponent is vulnerable to your hits, only the exact same pairing will generate a vulnerable hit as well. For example, if I have Air/Earth armor, I will exploit vulnerabilities against Air and Water elements, and a double vulnerability towards Air/Water pairings. Only another Air/Earth suit will give us both a vulnerability, and I’m vulnerable to any magic or earth armors.
Remember what I said before– Defense is good in this game. You need to be able to absorb hits, so the less you’re vulnerable to, the better.
The Staggered Element method: This is the opposite of the “Paired Element” method. The armors selected are not directly related. Thees armors are Air/Fire, Air/Magic, Water/Earth, Water/Magic, Fire/Magic, and Fire/Earth. The advantage is you increase the odds to hitting on a vulnerability. The disadvantage is you increase the odds of a vulnerability played against you.
If you have a set that is Fire/Earth, it exploits vulnerabilites against Magic and Air. The double vulnerability it exploits is Magic/Air. But note that in even having the double vulnerability it exploits, it has a vulnerability to the Magic portion you’re opposing! With the Paired Method, you’ll never have that issue – exploiting double vulnerabilities is always to your advantage.
The Unmentioned Single Element Battle Group: I didn’t mention just fielding single elements. I don’t see any particular disadvantage here other than you minimize what you exploit. I have also not been impressed with most single-element Legendary armors. That being said, Epic single elements, like the Northerner’s Armor and Blazeborne Vanguard, are particularly awesome and should be fielded all the time.
Should you vary your element sets? Maybe. Think about it this way. If you field 3 Air/Earth armor sets, one opponent with a set of Earth/Magic armor is going to mess you up big-time. However they have to field that armor.
Personally, I vary magic sets, because variety is the spice of life. It should be noted I rarely field Staggered Element armors in anything I do.