|This build uses the full power of Siegmund's follow up ability in addition to his huge attack to easily dispatch his any foe he fights. Ephraim is able to use his strength to overpower red, blue, and even some green threats while also giving him a strong supporting role for his team.
The optimal boon for this build is +Atk. This is to maximize the power of his guaranteed two attacks on initiation. His best bane becomes either -Spd, because he doesn't need it to double his enemies, or -Res, as it only has very limited use against Dragons and Close Counter mages.
Siegmund is centerpiece of this build, with the special skill refine. The special skill allows Ephraim to always double his enemies on initiation, allowing him to mitigate his biggest weakness: low speed. As long as Ephraim is above 90% HP, generally being just the first combat, Ephraim can automatically perform a follow up attack, regardless of the enemy's speed. This allows Ephraim to mightily increase his kill potential, allowing him to not rely simply on OHKOing or having to tank two hits.
Reposition is a staple skill that increases mobility options on a team. However, many other skills such as a dual rally could also be good depending on the team composition.
Bonfire allows Ephraim to pick up kills on tanky targets he otherwise would not be able to by adding consistent damage to his secondary attack when boosted by Heavy Blade 3.
Other possible specials include Luna, Moonbow to always have the special go off (especially if you're not running Heavy Blade 3) and Aether, which sacrifices some first fight potential for a large burst and heal on the second combat.
For Ephraim's A skill Death Blow 3 becomes the premium choice. Due to his ability to automatically follow up when initiating, Ephraim wants to simply stack as much damage as possible.
Other possibilities for A skills include Sturdy Blow 2, which gives Ephraim some added bulk when initiating into physical enemies at the cost of some attack. At base, when using Sturdy Blow 2 Ephraim can tank a red unit with 50 or less attack and still be within his weapon's range without having to heal.
While Ephraim's B skill is extremely flexible, Swordbreaker 3 is overall the best skill. Because Ephraim automatically follows up, the B skill he uses focuses on defensive potential. Due to the ubiquity of high power sword threats, Swordbreaker 3 allows Ephraim flexibility on either attacking them on player phase or defending against them.
Other options for B skills include Lancebreaker 3 for similar reasons, Guard 3 in order to mitigate one shot counterattack builds, or Renewal 3 to play the long game and heal Ephraim back up to his special weapon's threshold.
Ephraim's C skill is also extremely flexible. He can run a skill such as Hone Spd 3 in order to synergize with the offensive buff of Siegmund, a Drive skill to provide support from a distance, or even Panic Ploy 3 in order to panic units before the first combat.
Ephraim's Seal choice is also fairly flexible. Heavy Blade 3 is a requirement if running Bonfire, Luna, or Aether. Given his innate high attack, stacked onto Death Blow 3, Ephraim rarely has trouble reaching the threshold required to get the two cooldown per hit.
However, if one chooses to simply run his innate Moonbow another Hone/Fortify skill would be optimal, allowing Ephraim to provide 3 buffs at once.
Overall, Ephraim is played as a nuke, able to completely eliminate one enemy of his choosing. Even if he is knocked out of his weapon's activation range he can still provide a lot of support with Siegmund, or run skills that allow him to go for round 2.