As with the current trend in recent patches, version 5.8 introduces yet another new Flame-Chaser as a playable character, which is Starry Impression a.k.a. Griseo. She is a PSY-type Physical Valkryie that uses a Cross as her weapon type.

In Elysian Realm, all you have to do to play Griseo is use Ultimate, Weapon Active, then spam the Ult button until you get 5 paint of different colors then use the 2nd Combo ATK by holding the ATK button and watch enemies get bonked by Griseo's Knight. And that is actually the whole playstyle of Griseo. If you manage to get her signature weapon, she can also proc Ultimate Evasion using weapon active, which works well with Star 2nd Core and Sakura's Signets. Otherwise, you'll have to proc Ultimate Evasion normally, by evading an enemy attack.

Reference Video & Strategy
This time around I am using Griseo's full signature set because of lack of time due to personal problems. So I am sorry if you wanted to see budget or cope builds.
With that out of the way, the main Signets I'm using are Star and Discipline 2nd Core. Star 2nd Core works best if you have Griseo's Signature Weapon but can still work without, although not as optimal because you'll have to proc Ultimate Evasion manually. Discipline 2nd Core on the other hand works just fine with and without the Signature Weapon. An additional note is that while I fought Vill-V in this video, fighting the other Flame-Chasers should be easier as they don't have the Elemental Shield as Vill-V do.
For support, I used Starlit Astrologos and Vermillion Knight from the beginning up until before Nihilus (because I kinda forgot to change support), then changed Vermillion Knight to Blood Rose for Nihilus, and Flame-Chaser fight. There's not much to say here as I think the reason why I chose them is pretty obvious.
For sigils, I started with [Rainbow of Absence] and [Because of You], so I can get extra Elysia Signets at F7. I swapped [Because of You] for [Dreamful Gold] at F6 after I have used it to generate a door for Elysia's Signet. For [Rainbow of Absence], I swapped it with [Veil of Tears] after I am done with Star's Signets and didn't change it anymore. Ideally, try to finish Star 2nd core at F8 and Discipline at F15.

Signets & Explanation
Elysia


Similar to the other Flame-Chasers, Griseo can get 2 Elysia Signets at the start. The first 2 that you should pick are River Forest and Starry Night as they are just a really good combo. The next one you should get is Azure Wind, especially when you have her signature weapon in which you will be able to proc Ultimate Evasion with Weapon Active. After that, you can go for Feathers and leave Cloud Valley for last. Starlit Astrologos' gather should be enough for the most part, or at least it is in my experience, so your mileage may vary.
PRIORITY
1. River Forest & Starry NightR
2. Azure Wind
3. Feathers
4. Cloud Valley

Griseo

Griseo's Signet, Stars, gets its 2nd core in this patch and will be the main core to use on Griseo (the character). The 2nd core makes the taint able to mix or blend with another taint, similar to how the Picasso Stigmata works. The blended taints are Orange (Red+Yellow), Purple (Red+Blue), or Green (Blue+Yellow) depending on which Enhanced Signet you have, and each of them lasts for 15s. Every taint also increases Total DMG by 15% and another 15% if the enemy is of countered type (Nexus Signet). The effect of the blended taints are as follow:
- Orange: Triggers time fracture for 2.5s and reduce enemy Physical Defense by 40% and Elemental Resist by 15% for 10s (6s CD).
- Purple: Increases the effect of Red, Blue, and Yellow taint by 40% for the duration of the Purple taint (15s).
- Green: Increases Total DMG by 25% for each taint in the Nexus Signet (Orange, Purple, Green) for the duration of the Green taint (15s).
PRIORITY
[Normal Signets]
1. Red taint
2. Yellow taint
3. Blue taint
[Enhanced Signets CORE 2]
1. Orange taint
2. Purple taint
2. Green taint

Aponia

Aponia's Signet, Discipline, also gets its 2nd Core in this patch. This core increases Exhortation regen speed by 100% each second and will launch an attack every 150 Exhortation that makes it so enemies take 10% more Total DMG with each hit, capping at 70%. The Enhanced Signets are all based on this attack and they are as follows:
- [You Shall Punish Evil]: Makes enemies that are hit with the attack 2 or more times take 40% Total DMG while recovering 5 SP.
- [You Shall Follow Good]: The damage dealt by the Nexus Signet's attack is increased by 40% and increases Physical and Elemental Breach by 0.25% of Exhortation for 6s upon hitting an enemy.
- [You Shall Answer Prayers]: The attack makes you enter Penance mode for 8s, during which the Valkyrie will take 30% less Total DMG and deals 40% more Physical and Elemental DMG, and also deals Adaptive DMG to enemies that hit the Valkyrie.
PRIORITY
[Normal Signets]
1. Bonus Exhortation
2. Basic ATK's Total DMG
3. Ultimate DMG
4. SP Regen (if necessary)
[Enhanced Signets CORE 2]
1. Physical Breach
2. Total DMG
3. Physical DMG

Extras
Vill-V
For Vill-V's signet, the only signet you really need to get is the weapon active CD reduction one and that is it.
Sakura
If needed, just grab the one that gives an extra Ultimate Evasion. Then if you had to pick again then go for either Total DMG dealt or increased Total DMG taken by the enemy.

And that is all I have to say, sadly can't make a Fervent Tempo guide due to time limitations but it is what it is.
Good luck and have fun trying Griseo in ER!

