Since I went full-pity on Chizuru I didn't get her to EX 2, which is what I would've needed to slot her into my team. So this is what I did instead, using pretty much every other meta CoW unit I had that was EX 2 or EX 3:

• Esther - DPS and phase 2 tank
• Skye - DPS
• Sylvie - Buffer, earth-imbue, wind-sealer, and phase 1 provoker
• Chow - Morale gen, reraiser, phase 1 tank and phase 2 provoker
• Kaito - Breaker, DPS
• Cressnik - Blinder, light imbue, morale gen, reraiser, misc healer

Notwithstanding the instant-death gimmick, if you don't have Chizuru the big challenge in this one is gaining enough morale, quickly enough in the 10 turns you have. That's why I break the fight into two phases:

Turns 1 to 4: Chow tanks with his LB and counters to gain morale and fill Skye's LB, while Sylvie passive-provokes the insta-death

Turns 5-9/10: Esther tanks, while Chow active-provokes the insta-death every turn, letting Sylvie use her build-up moves

With this team, the big challenge is every three turns on turns 2, 5, and 8 the Manticore gains accuracy and self-heals his blindness, and Chow just doesn't have the DEF levels necessary to withstand that punishment. (I probably could've made this fight a lot easier with Maeve, but I only have her at EX 1.)

Every other turn, Manticore is blinded by Cressnik and that plus Skye's 50% accuracy-down and as much evade as I could get (100% on Chow, 95% on Esther's base form) he is relatively safe. But turns 2, 5 and 8 he will wreck you if you don't have a way to mitigate that damage.

The other thing to note is that this is an Earth team, and the Manticore will give itself a 2-turn DEF/SPR buff every turn you don't hit it with Wind. The first few turns I just live with that, since the focus is on building morale anyway, but from turn 4 onward I have Sylvie switch to her BS form which is equipped with a wind weapon, and she always makes sure to use at least one attack ability.

Build-wise:

• Esther is built for DPS in base form but notably has 95% evasion (50% innate 15% from Gothic Amulet 30% from Sea Dragon), then BS is mostly about DEF but with some extra evade and light-resist (since the enemy is imbued with it)
• Chow is built mainly for 100% evade with some DEF, but notably 2x Blizzard Orb and Looming Wrath. His BS form doesn't really matter (but I use it to chain anyway)
• Skye is built for DEF in her base form, not that it helps much, with a couple sources of guts
• Sylvie is built for DEF and has a wind weapon in her BS form, as well as Phoenix esper for the self-reraise turn 1
• Kaito is DPS, to the moon. Stays in BS the entire fight. Has innate guts.
• Cressnik is built for DEF

I'm not going to give a blow-by-blow but here's the synopsis of it:

• Esther and Kaito turns 1-4 just swap between BS and LB chaining, both to get Esther's field out there and get Kaito's 90% breaks up and running.
• Generally prefer Chow instead of Cressnik to do the re-raise since Cressnik's moves generate more morale

Turn 1:

• Sylvie does her self-reraise, since Chow needs to do his LB and Cressnik wants to do Arcane Stimulant

Turn 2:

• Sylvie imbues the team with Earth, and burns her base form Magnus (since she needs to stay in her BS after turn 3, she might as well use it for morale)
• Cressnik imbues the enemy with light (remember, this is the turn where he goes apeshit on the team)
• Chow builds morale and re-raises

Turn 3:

• Sylvie does her elemental resistance moves (which also put up the 75% physical mitigation, which is very important!)
• Chow nees to LB again
• Cressnik reraises Sylvie
• Kaito does his Torrential Force 1 (burst on Turn 7)

Turn 4:

• Sylvie switches to BS and does her morale-building attack (seals the boss)
• Cressnik removes the elemental imperils on the team
• Having stacked her LB, Skye switches to base form and just chains.
• This is a good turn to get the 100-chain. Esther Kaito LB, and Sylvie and Skye BSx3 hits 108 or so.

Turn 5:

• From this turn onward (other than the burst turn), Chow must always use his active provoke. (Typically can do both that and reraise on himself and one other move.)
• This is a high-damage turn, so Esther goes BS and uses her regular physical cover move (NOT her LB or omnicover magnus, both of which don't mitigate as much). Do NOT use her 10T CD, as you'll need it for turn 8.
• Chow uses his Focused Inspiration for the 50% beast mitigation.
• Sylvie uses her Earth magnus in preparation for burst on turn 7, and builds morale (seals the boss).
• Kaito should be able to do his 150% morale moves now
• Skye can use her magnus in base form for the extra 5% spear imperil
• Cressnik should use his party-wide reraise CD just for safety
• Esther typically takes a walloping this turn, but so long as she doesn't die it's fine, and even if she does then the reraise gives her a good shot of surviving to the next turn (and Sylvie will auto-imbue her, yay). Make sure you have her DEF HP fully potted!

Turn 6:

• Manticore is blinded again but still dangerous, and Esther is low HP and needs to go back into base form where she relies mainly on evade.
• Chow and Cressnik should focus on healing Esther as much as possible, and use the morale action to heal as well.
• Sylvie uses Beaten Insect on Esther (burst next turn), and builds morale.
• Skye uses Taivas' Spirit
• Esther uses her magnus in base form
• Kaito can do pretty much anything, but it's a good time to use his debuff-lengthening magnus so that you don't have to worry about them in the coming turns

Turn 7:

• Burst turn!
• Sylvie uses her BS LB
• Kaito uses Torrential Bladestorm
• Chow can chain with Kaito in BS form (or give him the EN materia if you like)
• No attacks from the enemy due to the 50% threshold, he just does a lot of buff renewals

Turn 8:

• It's tempting to prep the next burst, but this is another heavy-hitting turn from the enemy, so put Esther back into her BS form and have her use her 90% mit 10T CD (you may need to use Sylvie's LB-building move to give her the 10 crysts she needs for it).
• Kaito should use Crashing Wave (removes the boss's general mit) and his buff-shortening magnus (removes the unremovable ATK/DEF/MAG/SPR buff)
• Sylvie should use her Earth magnus to get the buff ramping up

Turn 9-10:

• It's up to you how you want to handle it, but you could potentially burst 49%-0% on turn 9 by having Sylvie use her Magnus on Esther for the LB fill enhance, plus Beaten Insect, plus her general attack CD. Then have Esther and Kaito chain LBs and Skye do her LB. I tried it with just the magnus and got down to 6%, then I added those other two and was able to hit 0%.
• If you can't burst all the way to zero, set up another burst this turn. Reraise is a good idea as Skye and Esther are both vulnerable.

Big wall of text, but I hope it helps someone!