Grand Hero Battle - Legion

I just finished this map in HELL difficulty without axebreaker skill(because I don't have). I'm F2P player so my low settings should work for you if you have the characters. I'm only listing useful skills.

Sanaki(+atk): Triangle Adept(A), R Tomebreaker(B), Attack+1(S), Moonbow
Soren(+atk): Darting Blow, Dragon Fang
Xander: Vantage, Bonfire, Quicken pulse(S) (Don't put FURY!)
Ninian: Hone Attack

Starting: Sanaki-topleft, Ninian-bottomleft, Soren-topright, Xander-bottomright

Turn1: Left two chars move up two spaces, Right two chars move up one space

Turn2: Red mage should dead, blue mage low hp, two axes same line with Sanaki, one left one right. Now use Sanaki and dancer kill the left axe, Soren kill blue mage. Xander move up two. End turn. Archer and right axe will attack Xander, with low damage

Turn 3: Two reins show up bottom, Soren move down 1 to kill blue with charged up special. Sanaki move down two attack axe, dancer go down left dance Sanaki then kill axe. Xander STAY on defensive tile WITHOUT attacking.

Turn 4: Archer will go to Xander's left-up, axe stay on Xander right. Both low health. One horse sword appear below Soren. Now, Soren move 1 right kill the axe, Sanaki move down-left attack horse, dancer move down left dance, Sanaki attack again, he is still alive, Xander down 2 kill him, only leaving Xander in range of archer. End turn, archer will attack Xander, die in Vantage. Up to this point, only one axe one lance rein alive from top. Lance will go straight down to bot-left of def tile. Axe will go to top-right def tile.

Turn 5: Last blue mage appear. Soren move left 2 to double hit lance, dance him, double hit again, kill. Xander still no attack, move 1 right, Sanaki move 1 right to attract blue mage. End turn. Blue mage and axe will move to left two def tiles.

Turn 6: This is NOT the time to attack. Xander move 1 right to the edge. Sanaki move 2 right to be out of blue mage's range. Ninian move to bottom-left corner, Soren move 2 left to edge. Only leaving Soren in attack range of blu mage.

Turn 7: Axe will move down 2, blu mage 2 tiles above Soren. They both have Vantage. Don't use Xander. He will die. Move Soren right-bottom to hit axe, then Sanaki left to hit him again. He is dead. Move Ninian 1 up to block the way of blu mage. Blu mage can only reach Ninian at this point, he will move back 1 space and attack Ninian, who is happy to take one hit.

Turn 8: Now it's Xander's show. Move left 3 space, Ninian down 1 dance him, another 3 space just a perfect distance to reach blue mage. He is dead.

Happy feathers!

Nino with Gronblade, Draw Back, luna, darting blow 3, desperation 3, hone atk 3 and the seal which lessens cool down

Azura with luna, Speed +3, Wings of Mercy 2 and Hone resistance 3 and spur Def seal

Lucina with reposition, aether, defiant speed 3, renewal 3, spur atk 3 and plus speed seal to not get doubled by legion

And default Klein (Any brave bow user can work)

My strategy basically was for klein to go on the offensive thanks to nino and lucina's atk buffs and Azura's dancing.
Klein basically was the one to chip and kill the legions, while nino was back up just in case klein needed help from range and Lucina as a shield.
I found it helpful holing up in the bottom right side of the map and making moves according to the situation. I hope this helps and good luck!

Tharja have axebreaker, skill lvl doesnt matter.
Hector have bonfire and reposition
Camus have drawback.
Place camus at the left bottom corner. Place azura next to it. Place tharja on top of azura. The hector on the right of tharja.
First use tharja to attack legion on the left, then use camus to drawback tharja. Then use hector to reposition tharja.end turn.
Use camus to attack legion, dance camus to attack red mage, use tharja to attack red mage. End turn.
Move hector to the bottom to kill newly summoned blue mage. Use tharja to attack legion, dance tharja to rigth and attack the other legion. Move camus to the left bottom corner again.
Use tharja to attack the archer, move azura to tharja former position to dance tharja. Use tharja to attack the archer again. Use camus to kill the red cavalry. Use hector to reposition tharja.
Use hector to kill the blue cavalry. Move hector from danger zone with dance. Move evryone from danger zone.
Use camus to kill blue mage cavalry, move everyone from danger zone. Use tharja to kill legion.

With LnD2 on Tharja and Nino and Speed+1 on Nino, these are my four fastest characters (38-41). Eirika has Fortify Res seal and rally defense which combined with Hone Spd and her weapon she can boost all four stats and make Nino and Tharja crazy fast killing machines, that even Legion can't stop (but damn did they get close!)

All were 5* but Xander.

Use Robin to break a wall and bait the archer. The next turn kill the blue mage with Nino and put Xander in the defensive title