Bound Hero Battle: Cecilia & Lilina

Explanations in Video Details
https://youtu.be/dlE-Aw2pIGw

Quad Archer with Draw Back (Summer Gaius, Setsuna, Bride Cordelia)
Dancer
Close Range Red Unit with Swap that can KO Cecelia
Close Range Blue Unit with Swap that can KO Blue Lance Unit and can survive hits from the Blue Lance Unit and Red Mage Unit.

For infernal, you will need inheritance to optimize units esp. ones with imperfect IVs. My Reinhardt is not perfect as he is +spd -def (not +atk).

Reinhardt is to handle the left side (Lance cav., Red wolf tome and Bow) while the others team up to face C and L (+Lance flier).
For this purpose, Reinhardt should have these skills:-
Dire Thunder
Luna
Death blow (esp. if you don't get +atk version of him)
R tomeBrk (if he is not +atk)
And you should consider these C-skill on other members:-
Hone cavalry
Goad cavalry
Ward cavalry - if you got -res of -hp version of Reinhardt, to save him from the wolf tome.
I use Goad on Camus, because my Rein is not +atk but neutral res.

Xander is to provide Hone cav. and to be emergency tank against Lilina, I also think Leo is also great for this job but I don't have him.
Cecilia is to provide Fortify cav. which is crucial for Xander to tank Lilina's strong magic attack, and with Hone cav. and Life 'n Death she is able to ORKO her doppelganger. She also major attacker on Lance flier.
Lastly, Camus is here to provide Goad cav. and being a clean finisher on Lilina.
Camus is definitely weak to Cecilia but he can tank some hit from her, I recommend Fury and Vantage build which makes him very strong on Enemy phase.

The strategy is as I mention above, Reinhardt will get ready in the tile south of the right breakable wall and put Xander next to him to provide Hone. In the next turn, move the buffed Reinhardt to finish Brave lance and move Camus next to the other side of the wall to provide Goad for Reinhardt.
The next turn, red mage shall commit suicide and leave Reinhardt at a little HP left, and the others shall break the wall and proceed to Xander's group.
If the flier approaches, Cecilia should take it out and remind to keep her out of Lilina's range with reposition from Xander or Camus, then Cecilia can take out Cecilia (hahaha) and Camus will wipe Lilina away.
For me, the tricky point is the archer which has ridiculous res and can KO Reinhardt in retaliation, I must put Camus near enough to goad Reinhardt.

Olivias * 2, with Wings of Mercy
Cordelia with Hone Speed, Reposition and Galeforce
Nino with Draw Back
Strat:
Nino, with Hone speed buff should be able to clear the blue flier. Cordelia then flings Nino to the backline, and with a dance from Olivia, Nino drags Cordelia a space back into safety.
On second turn, Cordelia first triple attacks the blue rider, then with a dance from Olivia, is able to take out Lilina.
Nino first takes down Cecelia and then the archer.
Then simply kill the red mage.

https://youtu.be/lRhVD4qNQOc

Essentially the same with different units

Marth can be any unit that can kill Cecilia in one turn (preferably a red melee)

Olivia can be any dancer at any level (preferably 4 star with the atk buff)

Reinhardt can be any ranged horse unit with reposition that can kill the Pegasus Knight and Lilina (Reinhardt, Olwen, Ursula)

Cecilia can be any horse unit that can reposition and kill the Blue Knight without taking damage from the red mage (Melee should consider drag back)

Good Luck!

Reinhardt and Camus have Reposition and Eldigan has Draw Back.

Reinhardt must be +Atk and heavily boosted in order to kill the Cavalier at the bottom left on initiation. I used Hone Cavalry boost from Eldigan, along with Death Blow, Quickened Pulse Seal and Moonbow to kill him. Then Reinhardt must have Red Tomebreaker to beat the Red Mage when he attacks you.

Camus has Lancebreaker so he can kill the attacking Pegasus Knight on next turn, Reinhardt kills Lilina, then use Danse from Olivia and Reposition / Draw Back from your Cavaliers to escape from Cecilia's wrath.