Corrin (F)

A sturdy physical tank to counter the strongest of sword and lance units, who also supports her 3/4 infantry team with special charge cool down and enemy debuffs and can take to the offensive if the opportunity arises.

My as of now +6 water dragon. Dark breath is such a great debuff move, initiate or take the hit she will most likely survive than debuff the attacker and any poor soul's close by. Renewal is there to provide longevity and be a pseudo healer also combos well with earth boost. Attack tactic is for my mixed team but can be switched with hone attack depending on the team.

The second member of my arena core, F!Corrin. Her dual defensive tactics make Camilla an unkillable cow goddess (and, pairing Camilla and Corrin together;))
The part that stands out is probably the Wrath+bonfire+Brazen atk/def. The goal of this build is to have her get knocked under 70%, then proceed to obliterate with a wrath boosted Bonfire, while being a physical tank. Dark Breath is there because it helps her tank better, while not being susceptible to Panic Ploy

Cripple your opponents while also buffing yourself like hell.

Skill slots are up to preference.

Specials/Assist is preference

Vantage can be replaced with windsweep, to ensure buffs go off.

Distant Counter is used for battling mages, but can be replaced if desired.

This Corrin build utilizes the Shield Pulse/Sacred Cowl combo, which allows her to become an extremely potent magical tank in addition to her high defense. A RES boon is preferred due to her having to take hits from tomes and other dragons, while the other bane is flexible. I prefer -HP, however, due to the temporary bulk not being necessary. Her refined weapon mostly patches up her weak attack with its 16 mt, and the +5 HP patches up the HP bane. Dark Breath+ in this case is superior to Lightning Breath, as the latter grants +1 cooldown - a normally trivial aspect that hampers this build’s effectiveness greatly. Sacred Cowl’s base CD is a measly 2, and that is negated by Shield Pulse 3, allowing Corrin to have Sacred Cowl up almost indefinitely. Aegis does not work for this reason as well because of its cooldown.
Swapping in to take hits then countering with Dark breath’s debuff works wonders against many teams, making it my preffered support skill. Reposition, Pivot, etc. are fine as well, and Reciprocal Aid/Ardent Sacrifice work too. The A slot is filled by a classic DC, which is essentially the source of her offensive power. Surprisingly, it is not vital and can be swapped out for a +RES seal or +SPD. Unfortunately DC is the only one that lets her hit back against mages, making it the main choice. The core of this build is Shield Pulse 3. This allows for Corrin’s nigh impenetrable ranged defense and is surprisingly a F2P skill - your free Fjorm comes with it in her base kit. Unfortunately, many players may not want to sacrifice a top tier lance for this build, so it is more oriented to people who have their lance slot filled out. Corrin’s native Hone Atk 3 is not too important, but helps the team secure KOs consistently, making it my preferred option. Finally, the Distant Defense seal contributes to her bulk greatly, but can be swapped out for a Deflect skill if you wish.
Corrin’s preffered team has a carrier - someone with guidance/reposition and high bulk and mobility (like cavalry or flier) to get Corrin out of danger or airdrop her in. A physically strong red such as Zelgius, Black Knight or even Chrom or Zephiel will check greens and duel Falchions. Bonus goes to BK and his counterpart as they have DC to take out Naga tomes. Summoner support should go to them and help with their low RES. Another option for the team is adding a green mage like Deirdre, Julia, or Nino to add firepower and check blues - I recommend using this option if you have trouble against Reinhardts or just want more coverage in general. I find that even with a +ATK refine, Corrin’s DPS falls a little short so I suggest packing another blue unit (maybe physical, as Corrin is a dragon). TA (Sapphire Lance optional) Azura would fit this role nicely, as she can ORKO a lot of reds that escape Corrin’s Dark Breath. The Sing is also invaluable, but if you need more firepower maybe switch to someone else.