Gatrie

Weapon: Spirited Spear+ (+Res) / Flowing Lance+ (+Res) / Slaying Spear+ (+Res) / Gilt Fork+ / Courtly Candle+ / Berkut's Lance

Assist: Positional Assist

Special: Aether / Moonbow / Noontime / Ignis

Passive A: Fort. Def/Res / Distant Counter

Passive B: Crafty Fighter

Passive C: Atk Smoke / Pulse Smoke / Armor March / Wave or Joint Hone skills

Sacred Seal: Sturdy Stance / Mirror Stance / Warding Stance

• For those wanting to put Gatrie to work with little investment, the Armored Amour fortunately makes this easy. Spirited Spear, Crafty Fighter, and Fort. Def/Res are skills that come natively on Gatrie and already offer a potent Enemy Phase playstyle combination.
  • Much like its predecessor Vengeful Fighter, Crafty Fighter grants the ability to retaliate against incoming enemies twice, allowing Gatrie to close kills more often in one match. Unlike Vengeful Fighter, however, it stalls the enemy's Special Cooldown, allowing Gatrie to come out of most matchups unscathed with little fear of getting cheated by a powerful Special.
  • While Vengeful Fighter's Special Cooldown acceleration is something to be missed, this is made up by Spirited Spear's own effects. That is, if Gatrie has a bonus active on himself (something that can easily be done with his own Wave or Joint Hone skills, or running ally support such as Armor March or Tactics skills), he gains acceleration upon enemy attack as well as a nice, handy boost to his Attack and Defense.  
  • Fort. Def/Res fortifies Gatrie's ridiculous Defense and investment-worthy Resistance quite well. It is replaceable with Distant Counter should you wish to combat distant enemies instead, though Resistance investment in other skill slots will be needed to make good milage out of it.
• The most tough choice you may have to make on this build would be choosing Gatrie's weapon. As there are many possible lances he can equip to improve his gameplay, here are a quick list of recommendations to consider depending on your needs. As a note, all lances should be Resistance-refined to balance out Gatrie's defenses and cover up his lower magical bulk, though you may consider Defense refining for pure physical performance. 
  • Spirited Spear comes by default on Gatrie and is usually sufficient keeping around, provided you remember to abide the lance's effects by giving Gatrie some sort of stat or movement bonus.
  • Flowing Lance is easily Gatrie's best general choice as it covers a variety of needs. It cancel opponent bonuses in Atk/Spd and further punishes these stats by -5, making Gatrie simply more spectacular in dishing out damage and taking even less of it both physical and magically. Keep in mind that these effects rely on Gatrie being at least one space away from his allies, which may not be ideal on setups attempting to help him move around with skills like Armor March or Guidance.
  • Slaying Spear turns Gatrie into a nice Arena / Arena Assault pick as armored units are very frequent in these modes and Gatrie can deal huge effective damage against them.
  • Berkut's Lance can be seen as a more accessible Flowing Lance in that it also significantly improves Gatrie's magical matchups. However, it lacks the added power and physical bulk of the previously-mentioned lances.
  • Gilt Fork and Courtly Candle are seasonal slight variations of Spirited Spear and Flowing Lance if you prefer their effects.
• Spirited Spear reducing cooldown by -1 on Gatrie's Specials means he can afford to run a few longer-winded choices.
  • Ignis and Aether, for example, will activate in two clean enemy hits, while Moonbow and Noontime only require one.
  • Given any other lance, priority should be given to shorter winded Specials as Gatrie otherwise doesn't have a way to accelerate his Specials (assuming no outsourced support such as Geirskögul).
• For the C slot, there are several particular options to consider.
  • Atk Smoke is the easiest relevant Smoke skill Gatrie can access and is generally best for all-purpose gameplay to reduce incoming damage. Pulse Smoke is a specialty Aether Raids Offense option—mainly to cripple precharge Pulse setups—if you plan on maining Gatrie in said mode.
  • Armor March not only improves Gatrie and his fellow armor allies' otherwise slow movement, but also counts towards Spirited Spear's effect conditions. Otherwise, you may employ other self-buffing bonus skills for this purpose.

Weapon: Flowing Lance+ (+Def or +Atk) / Slaying Lance+ (+Def or +Atk) / Spirited Spear (+Def or +Atk) / Slaying Spear+(+Def or +Atk)  / Brave Lance+ (+Def or +Atk)

Assist: Positional Assist

Special: Bonfire / Ignis / Moonbow / Galeforce

Passive A: Atk/Def Solo / Death Blow

Passive B: Bold Fighter

Passive C: Armor March / Armored Stride

Sacred Seal: Death Blow / Quick Riposte / Sturdy Blow / Armored Boots

• Simple man, simple build. Hit fast, hit hard, hit often. Such are the mottos of a build based on Bold Fighter, which allows Gatrie to take an aggressive approach with an added follow-up attack in Player phase. Thus, Gatrie can yet again overcome a Speed stat that rivals even Arden in absolute slothfulness.  
• To make the most out of this build's aggressive approach, high damage modifiers are considered in both the A slot and Sacred Seal slot.
  • Death Blow in both slots is as simple as Gatrie himself, giving him the highest reliable damage modifiers possible besides Brazen skills.
  • For reliable dual phase performance, Gatrie make take Atk/Def Solo which increases both his Attack and Defense by a very considerable amount. This can be paired with Sturdy Blow for further Defense building and Bonfire damage, or Quick Riposte for the classic second-generation dual-phase build, giving Gatrie a follow-up attack in both phases.
• There are a ton of lances which serve to help this build's damage potential. In short:
  • Spirited Spear comes by default and also fortunately works in Player phase, assuming you abide its condition by giving Gatrie a bonus (such as Tactics or his own Armor March or Armored Stride or Armored Boots).
  • Flowing Lance is technically a more reliable version of Spirited Spear as it effectively grants a better Atk/Def swing while encouraging Solo conditions.
  • Slaying Lance gives way to some rather frightening Special combos with Bold Fighter thanks to permanently reducing Gatrie's cooldown by -1.
    • With it, Bonfire reliably activates against many opponent whether they counterattack or not, while Ignis will require a counterattack but yields more burst damage. Galeforce also reliably activates in two hits without a counterattack needed.
  • Slaying Spear decimates nearly any bulky armored foe Gatrie comes across with its effective damage.
  • Brave Lance offers more blitz damage per hit while activating some Specials quicker in combination with Bold Fighter's acceleration.

Weapon: Slaying Lance+ (+Res)

Assist: Positional Assist

Special: Sol / Bonfire

Passive A: Fort. Def/Res / Distant Counter / Various Atk/Def or Atk/Res Bonds, Unity, or Solos

Passive B: Special Fighter

Passive C: Atk Smoke / Pulse Smoke

Sacred Seal: Quick Riposte

• Here it is, a build so performatively good and conventional yet so uninteresting that the writer is wondering why you're not just using Crafty Fighter + Spirited Fighter or Slaying Lance + Crafty Fighter + Geirskögul for basically a similar and cheaper build, or even refining Brave Hector or Gwendolyn's weapon for this.
• Admittedly, though, Special Fighter + Slaying Lance does yield higher immediate results on 3 CD specials (which would be Sol or Bonfire depending on your preference for recovery versus damage) than Spirited Fighter + Noontime does. That is, in return for better Special activation and returns per hit, Gatrie sacrifices stats from the first build.
• Like its Crafty counterpart, Special Fighter also stalls enemy Specials by inflicting Special cooldown +1 on them, though the accompanying effect is accelerating Gatrie's own Special (hence immediately activating Sol and Bonfire upon every counterattack) while being timed at a shorter 50% HP threshold rather than 75%.
• As a result of now lacking a way to attack twice from losing Crafty Fighter, Quick Riposte in the Sacred Seal is most certainly a given. Note that this, too, is timed by another inconvenient HP threshold of 70% HP, which can be kept by healing from Sol or other outsourced methods (like a dedicated healer or healing skill such as Sparkling Boost).
• The only non-straightforward aspect of the build is choosing Gatrie's A-slot.
  • Fort. Def/Res is already pretty good for this as it boosts both defenses by a ton and comes on Gatrie's default kit already.
  • Distant Counter whacks two-range enemies who would otherwise take advantage of Gatrie's melee status and lack of movement/escapability options.
  • The slot is otherwise open for any Atk/Def or Atk/Res-related skills you can offer. Atk/Def Unity and Atk/Def Bond, for example, make Gatrie effectively impervious to attempts to debuff him in those stats while requiring him to only park near his allies.