Eldigan

Weapon: Dark Mystletainn (+EFF)

Assist: Positional Assist / Flexible

Special: Bonfire / Luna

Passive A: Distant Counter 

Passive B: Vantage 

Passive C: Def Smoke / Pulse Smoke / Savage Blow / Joint Drive Atk / Cavalry Buffs / Flexible

Sacred Seal: Atk/Def Solo / Quickened Pulse / Fierce Stance 

• Eldigan shines with a standard Vantage nuke set thanks to his solid base Attack and access to Dark Mystletainn, granting him strong OHKO potential through strong base damage on top of instant Special activations on each counterattack. Since the primary goal of this set is to cleave opponents with one hit, a +ATK IV is crucial here. 
• Dark Mystletainn’s combination of a Slaying effect, Special Spiral, bonus Attack and Defense, and an additional +7 damage on Special activations makes his nukes very potent, and those with three-turn cooldowns are particularly exceptional as they will always be available after their initial activation. Of those available, Bonfire is generally best as it takes advantage of the entirety of Dark Mystletainn's effects, but Luna may still be considered for stronger burst against bulkier foes.
• Beyond his Special choice, the power of this set lies in Eldigan’s choice of A and B skill: Distant Counter and Vantage. When utilized in tandem with Dark Mystletainn, Eldigan serves as a strong check to melee and ranged foes alike and hit them with the full brunt of his Special before they can even land their first attack.
• Eldigan has a few different options for his C slot, most notable of which are Smoke skills; through the AoE debuffs they apply on enemy foes, they naturally complement a defensive playstyle such as this one. Def Smoke is ideal from a damage perspective—or potentially Savage Blow if unavailable—though if using him within the context of Aether Raids Offense, Pulse Smoke is highly recommended to shut down Infantry Pulse setups. Joint Drive Atk is another potential candidate for dual buffing utility, or cavalry buffs when running him alongside other mounted allies. 
• His Sacred Seal slot should be occupied by something that enhances his key stats—namely Attack, but also Defense if using Bonfire as his Special—or Quickened Pulse to ensure his Special chain activates immediately in his first round of combat.

Weapon: Dark Mystletainn

Assist: Positional Assist / Flexible

Special: Blazing Wind / Blazing Light / AoE Specials

Passive A: Life and Death / Fury 

Passive B: Lull Atk/Def / Chill Def 

Passive C: Def Smoke / Savage Blow / Cavalry Buffs / Flexible

Sacred Seal: Life and Death / Hardy Bearing / Quickened Pulse 

• Refined Dark Mystletainn pairs quite well with AoE Specials as well; the interaction between the weapon's effects and these Specials lets Eldigan consistently fire them off without delay following their initial activation, and Mystletainn's refinement allows Eldigan to potentially tack on +7 damage to their damage as well. Increasing Eldigan’s base Attack with an Asset is once again recommended to maximize his damage potential. 
• His choice of AoE Special is entirely dependent on personal preference, but Blazing AoE Specials are generally preferred given their higher damage modifier with Blazing Wind and Blazing Light having the most generally useful ranges among those. 
• It’s crucial to keep in mind that the damage calculation for AoE Specials involves visible stats only and does not account for any in-combat boosts that may be in play. This makes any sources of visible Attack quite useful, thus rendering Life and Death the prime A skill to use here for its massive boost. Alternatively, his base Fury helps Eldigan retain his strong Defense in exchange for being weaker. 
• Eldigan’s B slot is flexible, but anything that can aid his damage will work well. Lull Atk/Def is a high-investment option that helps him push past enemy buffs against an opponent already weakened — but not outright KO’d — by his Special. Chill Def is another choice if sources of visible Defense debuffs are not available, though it does come with the detriment of not being targetable. 
• Def Smoke and Savage Blow help supplement Eldigan’s OHKO potential, with the former being quite valuable when refresher support is available. Otherwise, feel free to plug anything into his C slot that synergizes with his team. His Sacred Seal options are split between further boosts to his visible Attack, Hardy Bearing to work around Vantage units, and Quickened Pulse to let him access his initial activation faster. 

Weapon: Dark Mystletainn

Assist: Positional Assist / Flexible

Special: Aether / Sol / Bonfire

Passive A: Sturdy Stance / Steady Stance / Atk/Def Solo

Passive B: Lull Atk/Def / Quick Riposte 

Passive C: Atk Smoke / Cavalry Buffs / Flexible

Sacred Seal: Quick Riposte / Mystic Boost / Atk/Def Solo / Sturdy Stance / Close Def

• This build once again highlights the Enemy Phase applications of Eldigan’s Dark Mystletainn, but shifts focus more towards his ability to tank hits from incoming physical threats. Besides increasing his Attack, taking a +DEF IV may be a worthwhile consideration to further reduce the amount of damage he may take. 
• Eldigan can make surprisingly great use of Aether for its simultaneous sustain and damage output increase, effectively reducing its base cooldown to two through Dark Mystletainn after its initial activation. This allows him to activate it in every round of combat through Quick Riposte —and if Brave Lucina, Summer Hilda, or New Year Velouria support is available, he can activate it on every counterattack. Other options include Sol to avoid needing too much setup (and is still not too much of a cost to his damage since Dark Mystletainn provides a +7 bonus upon any Special activation), or Bonfire if a healing Special is deemed unnecessary. 
• Any A skill that enhances either Eldigan’s Attack or Defense — or both — will work well here, with some standouts being Stance skills for their Guard effects or Solo skills for the pure amount of stats they provide. For his B slot, he benefits notably from Lull Atk/Def to obtain a greater stat advantage or Quick Riposte to ensure his follow-up. 
• Smoke skills are excellent choices for Eldigan’s C slot to supplement this build’s defensive playstyle, with Atk Smoke generally being the most effective at strengthening his survivability when tanking multiple opponents; however, as always, this is flexible.
• The Quick Riposte Sacred Seal works excellently if it’s not already in his B slot, though it may be unnecessary either way if using a more OHKO-oriented set with Aether and Brave Lucina, Summer Hilda, or New Year Velouria. Mystic Boost also works well to give Eldigan another source of healing and potentially eliminate the need for a healing Special altogether. If nothing else, anything that augments his key stats is solid filler.

Weapon: Mystletainn (+Eff) 

Assist: Positional Assist / Flexible

Special: Glimmer / Bonfire / Moonbow 

Passive A: Fury / Death Blow / Sturdy Blow / Brazen Skills

Passive B: Lull Atk/Def / Wings of Mercy / Vantage / Chill Skills

Passive C: Def Smoke / Rouse Atk/Def / Wave Skills / Smoke Skills / Flexible

Sacred Seal: Brazen Skills 

• This build centers around the use of Eldigan’s original refined Mystletainn — specifically, the self-inflicted damage it applies via its innate Fury effect. This allows him to safely reach lower levels of HP with each passing round of combat, which he can utilize to his advantage with specific skills like Brazens alongside his PRF’s additional stats for enhanced combat potential. That being said, the focus is once again on his damage so a +ATK IV is preferred over all else. 
• Pairing refined Mystletainn with Fury in Eldigan’s A slot provides him a substantial boost to his visible stats across the board, while making it faster for him to activate low health-dependent skills given his surprisingly high HP pool. Alternatively, one can invest fully on front loading Eldigan’s damage through skills such as Death Blow and Sturdy Blow.
• Lull Atk/Def is a great generalist B skill that pushes the Lionheart’s damage cap and survivability further while helping him push past any visible buffs the enemy may have, while Vantage helps grant him some Enemy Phase functionality. If using him in a team composition centered around low HP units, Wings of Mercy may be worthwhile to expand his mobility. If nothing else, one can always use Chills to support both Eldigan’s and his allies’ performance. 
• Def Smoke shines when Eldigan is provided with refresher support to enhance his damage considerably against nearby foes, but self-buffing skills that affect his Attack such as Odd Atk Wave and Rouse Atk/Def also work to make him less dependent on team support. For his Sacred Seal, an Attack-increasing Brazen skill will work wonders to build upon his performance at low health.