I assume that you've researched how to clear Elemental Sanctuary on Easy, right? Are you enticed by the amount of Cosmo that drop here? Have you heard that Normal difficulty Elemental Sanctuary won't drop any B-class Cosmo? Excited now?

So here follows a few strategies for how to complete Elemental Sanctuary on Normal.

1. Saints

I would recommend the following lineup:

Chameleon June (1st SPD), Cepheus Daidalos (2nd SPD), Sextans Luna (3rd SPD), Scylla Io (4th SPD), Eagle Marin (5th SPD), Pisces Aphrodite (6th SPD)(Of course, the only one who cannot be switched out is Marin; all other Saints can be exchanged) But remember, your party must consist of both physical and cosmic damage dealers!

To be honest, the Saints you select for Elemental Sanctuary don't really matter, but they do need to be of quite high levels. I recommend all support-type Saints to be at least level 70, and your main damage dealers to be at level 80. As Inferno Elemental attacks with Physical Attack + Cosmic Burn, and Iceshard Elemental attacks with Cosmic Attack, I recommend using the Lunar Cosmos [Bloom] or [Dual Defense] of at least +10 to make sure they have enough HP to survive. If you're still worried about not surviving, you can add June to your lineup, making the fight much more stable.

(Of course, the only one who cannot be switched out is Marin; all other Saints can be exchanged) But remember, your party must consist of both physical and cosmic damage dealers! 

2. Training Skills

In the beginning phases of the battle, it is accompanied by Daidalos and Seiya, and Seiya's single-target attacks are powerful enough to easily one-shot your Saints. That's why you should focus on controlling one of them and focusing the other one down. Seiya probably won't use any skills during the first two rounds, so your best bet is probably to focus down Daidalos and control Seiya.

3. Cosmo

I would like to recommend a Legendary Cosmo—Kingfisher.

Are you aware? When critting, Kingfisher has a 70% chance to deal true damage! This true damage makes it possible for physical attack Saints to damage Inferno Elemental when critting. If you don't believe me, just check out the picture.

What do you think? Inspired yet? That's right, for Aphrodite, we've chosen to use the Legendary Cosmo Kingfisher in order to make up for the lack of cosmic damage.

As for Cosmo for your other Saints, be sure to pick Cosmo with high HP and C.DEF, thereby ensuring your party's survival.

4. Battle

Whatever lineup you choose, you should be wary of the following:

    a.     You have to first focus down or control Seiya. To focus him down, use June + Io, or June + Milo, or Seiya's Weaken debuff + another damage dealer, or even silence him with Black Cultist or stun him with Moses.

    b.     When the boss drops below a certain HP percentage, it will begin by summoning Eagle Marin, and then Aquarius Camus. When that happens, be sure to focus them down as quickly as possible, especially Marin as her healing ability will make the fight much more difficult.

    c.     The boss will also apply an [energy cost increase] debuff to your strongest damage dealer, which will force you to think more carefully about how to spend your energy.

    d.     Remember to leave 1 energy for Marin's heal, and if the debuff lands on her, you have to leave at least 3 energy.

    e.     When one of the bosses drops to below 70% HP, the left boss (fire) will become immune to physical attacks and the right one (ice) will become immune to cosmic attacks. If your party mainly consists of physical damage dealers, I would recommend focusing on the Inferno Elemental in order to trigger its physical immunity shield.

    f.     When one boss is about to die, it will recover HP equal to an average of the other boss' HP. So, just focus your damage on the two bosses.

    g.     When one boss drops to the ground, you have to kill the other during the same round, otherwise the one you kill first will revive. However, do not fret! We have a secret weapon—the Legendary Cosmo Kingfisher. When both bosses are low on HP or if you have already taken out the Iceshard Elemental,  Aphrodite will be able to finish off Inferno Elemental without breaking a sweat! (Of course, this requires your Aphrodite to have a high chance to crit)

As a final note, be sure to keep track of the rounds that are displayed in the top-right corner. You have to kill the bosses during the allotted rounds.