Raven

Its quite a troll set with how it relies on his hp going down and is a complete player phase beast. Still can't outshine units like dorcas or Brave Ike but can still be really fun. This Raven works really well when you have tana on your team or just guidance in general.
You can replace Brazen Atk/Spd 3 with Fury 3 but that works better with a -res raven rather than a -hp raven. Atk Tactic 3 can just be replaced with Hone attack as well.
Pros:
-Fun
-Cheap?
-It works
Cons:
-What happened to Dorcas?

Ever since release, Raven has been a powerful axe unit and retains that position somewhat as the best infantry axe unit, debatably only overshadowed by Dorcas (who admittedly serves a different purpose.)

This build aims to emphasize Raven's strengths while keeping in tact what separates him from other axe units. In this vein, I'd suggest a +Speed or +Attack Raven. You'll need to make slight adjustments based on which IVs you're working with, and I think said adjustments should be rather obvious.

This build starts with replacing his default weapon in favor of a Slaying Axe+. While I suggest a +Speed refinement, you can also do a +Attack refinement if you prefer. Alternatively, if you don't have a Killer Axe+ to pass and refine or similar, Raven can work with a wide variety of axes and perform similarly, such as the Melon Crusher or Legion's Axe+.

For his support, it's up to your preference. In the name of arena points, you can run a dual rally skill or if that doesn't particularly matter to you you can just run whatever movement skill strikes your fancy.

Now, onto his passives.

As an infantry unit, Raven has a huge advantage over his mounted counterparts, that being access to infantry/armor exclusive skills. Now, I'm sure you're probably thinking "oh my gosh steady bReath!!!!111!!1!!one!!!" but with his eh defenses, it's not quite ideal for him and honestly without high investment I wouldn't suggest it. But, there are some other options I think really help him out.

For his A skill, Fury is a fine choice, increasing his bulk a bit but giving his offensive stats the push they need to be absolutely nuts. Seriously, with a +Speed Slaying Axe+ and +Speed nature he'll boast an amazing 44 speed and a decent 51 attack.
Along that same line, Swift Sparrow is also a great option, letting Raven increase his juicy offensive stats without killing his defenses and is my personal preference.

For his B skill the easiest answer is Desperation. Given his speed and newly found low cooldown, you can't really go wrong with this and can synergize well with Fury especially if you're not super comfortable putting him in danger. However, his status as an infantry unit comes in here, and Wrath is a possible option for him to run as he does benefit quite a bit from both of Wrath's effects and they work nicely with the Slaying Axe+.

For his C slot skill, Threaten Defense is his default and for a reason as he does great with it. If you need a little more doubling in your life, Threaten Speed is a fine option. Of course, simply choose whatever your team needs.

For his special, you have a variety of options. Aether and Galeforce are fine options especially if you have Infantry Pulse units on your team. Otherwise, Draconic Aura will serve him well or alternatively Luna if you're not a fan of Draconic Aura or simply don't have it available.

For his seal, simply run Attack +3 or Speed +3 (or their squad assault equals), whichever you prefer. However, if you'd like to bolster his efenses, Close Defense or Deflect Melee are fine options.

When Raven first came out... he was an interesting unit, Specializing in Atk and Spd while the rest is decent. But when Weapon Refinery came out, he became much easier to use and is preferred over units like Legion due to having available IV’s. With the Slaying Axe+ being more common now, Raven can reach 58 Atk while at being at only +1, which isn’t hard

Set details:

Weapon- Slaying Axe+ - with good MT and access to Speed +3 and HP+5, Raven can now be at a safe speed stat so that B!Lyn won’t kill him, it does get rid of possible 60 Atk but 58/41 is really good. (It is also the safest possible way to boost speed without sacrificing Atk that much)

Assist - Reposition (Self explanatory)

Special- Draconic Aura: 2 Cooldown is really good for such a powerful skill like DA, it complements his really high Attack stat and it charges quick. Dragon Fang is another option but has a slower cooldown at 3

A Passive- Fury: Hey... every build needs either Fury or LnD these days but Fury has no draw backs thanks to his B Passive

B Passive- Renewal: any B skill work for him but having Renewal makes a safe way to off set Fury Damage... otherwise Desperation is good to use, but the speed competition has been making the skill Fall

C Passive- Threaten Defense: Anything works here but Raven’s Base Skill is cheap and is good on him

Seal- Attack +3 (Squad Ace E) works because it makes his Attack even higher

This build allows Raven to deal a heavy amount of damage and consistently double most units and some of the faster lance units such as Catria, Brave Lucina, Tana, or even Nephenee. Of course, with the +Spd and Lancebreaker, even will of course double the fast lance users. And if he is having trouble killing them if they have bulky defense, then Threaten Def helps deal the extra damage that Raven needs to finish them off. And since Slaying Axe+ reduces cooldowns by 1 and since you run Quickened Pulse, Raven will have Luna ready to use on the first attack and he will be able to make it a 2 turn cooldown, making him more useful against the lance users and even some of the better sword users.

This build focuses on making Raven a tank while not compromising his good offensive stats. Slaying Axe+ gives Raven a good source of damage and allows him to charge his special faster. Close Defense 3 in his A slot and Distant Defense 3 as his Sacred Seal allows him to reliabley tank enemies at any range. Aegis is used to patch up his bad Resistance by helping him tank magic hits. Renewal 3 is used to keep his HP topped up so he can keep fighting. Atk Ploy 3 is used to reduce the amount of damage Raven takes in general.