Bound Hero Battle: Alm & Celica

Azura: Fortify Def 3 and Fortify Res 1 seal
Olivia: Hone Atk 2
Bridal Cordelia: BB+, DB3, Atk seal
Reinhardt: Dire Thunder, Fury 3, Hp seal

Azura and Olivia can be put on either side of Cordelia so that she gets their buffs. Once the turn starts move Cordelia into range of the green mage and let him hit her, she'll hang on and revenge kill the next round with the BB+. Then use Olivia to grant Cordelia another turn to take out the blue mage.
Move Azura to the left of the rubble wall and keep Cordelia in front of it. Move Rein to the left of Olivia and end turn.
Turn 2 move Rein in to attack Celica, use Olivia to allow him to finish her off. Move Cordelia to attack and finish of the blue cavalier. To end the turn have Azura block the entrance to the left.
Turn 3 attack Alm with Rein, use Olivia to let him finish him. Move Azura out of the way and have Cordelia finish the battle by attacking the green flier.

IV's should not matter, but here were mine.

Lucina is +HP/-Res, Defiant Spd/Knock Back/Spur Atk 3/Luna/Falchion

Azura is +HP/-Res, Spd +3/Renewal 2/Fortify Res 2/Glacies/Sapphire Lance+/Sing

Camilla is +Spd/-HP, Darting Blow 3/Savage Blow/Brave Axe+/Draconic Aura

Lissa is +Atk/-Res, HP +5/Renewal 3/Threaten Res/HP+3 Seal/Fear/Rehabilitate/Swift Winds Balm

Lissa can be replaced with any healer that has Rehabilitate and Swift Winds Balm/Kindled Fire Balm depending on your team and its stats. It does not matter the defensive stats, as the enemy should not go after the healer. Every time I completed the battle she did not take any damage.

Turn 1: Have Lissa, Azura, Camilla, and Lucina ordered in that way from left to right. Have Lissa break the wall, then Azura jump to her left and sing. Lissa takes cover by moving one space below and Camilla moves to where Lissa was with Lucina moving right next to her. The enemies will become baited out with the Blue Mage dealing around 7 damage to Camilla.

Turn 2: Have Camilla move up (after being healed) and take out the blue Mage, which fills up her skill gauge entirely. Azura then moves up to her left and sings so Camilla returns to the space she was in leaving Alm's range. Lucina remains in place. Azura will be in range of the green Mage and take quite a bit of damage, but mine was -Res and survived the attack with 7 health remaining. If your Azura is -Res/HP and +a different stat she may end up dying, I'm not entirely sure.

Turn 3: Lissa goes to the space below Azura to heal her, if Rehabilitate is equipped it will return her to max. Lucina moves up and attacks and takes out the green mage, Azura sings her to return Lucina to the space she was at and Camilla moves to take out the blue lance user. If she quads and activates skill, she will take no damage. Alm and Celica both target Azura, bringing her skill gauge to max without losing much health.

Turn 4: Lissa attacks Alm to chip him down, while Lucina comes in and finishes him off, her skill gauge should be charged to seal the deal. Azura then attacks Celica, if her skill is charged and her resistance high enough, this should take out Celica.

I have been playing since launch and not spent a single dollar for orbs. Most of the skills given were in built skills. This team probably doesn't work on Infernal Difficulty.

I use the same ideas as the team like the spam wizards infernal in the recently post, but a little different, not much. :)
My teams is all 5*, except Olivia.
My Rein is +spd/-atk, normal skill sets with reposition, spur atk 2 and squad ace seal.
My Nino has +spd/-def, +atk seals, normal skill sets with a slot fury 3, b slot desperation 3, special moonbow.
My Tharja is +1, +atk/-res, hp +3 seal, normal skills set.
Olivia lv 40 (40+ is ok.) has fortify res seal.
Just don't too worry about the stats. :)
Try and you will know how to change. :
Start position is O, T, R, N.
Then you place T in the range of green mage near right entrance, the 4 block of 6.
N stay where she is.
R repo O, place O under N.
(Ur choice to place R under Y by using N dragback).
Then N kill blue lance.
T kill green mage.
Dance N in blue mage range and atk Alm, use R to repo T.
Then when blue mage kill by N, move her near O (probably near bridge ,if it's true then u are following the right way :) ).
Use R kill Alm.
Move O down the bridge and T out of green axe range.
Then after C atk R, use T or N to kill green axe.
Then try to bait C out of her Defense block where O can atk C, R can have hone atk buff and finish her (but still hide other characters, probably the easy place to do it is the right wings, where ur team on the left wings with C on the right wings).
Hope this could help u guy, cuz it's really a hard map.
Goodluck. :)

A bit of luck on clearing this battle. The main goal I did is to not let anyone cross to your side, while you reduce them one by one.

Just be careful of Celica, because Celica hits really hard, especially at full HP.

Use the color triangle, Linde. Use the color triangle.