In this guide I will aim to give you an in depth idea of what the Feca class can achieve, where they excel, how to build a Feca and what are some of the best sets for a Feca.
Characteristic Points
Intelligence. The intelligence Feca focuses on dealing damage from range. The Int Feca's damage is really good although the main point of playing Feca is to Tank and shield your allies. The Dofus Touch Int Feca is the best build IMO.
Strength. Strength is the Feca's close combat build. On the PC Dofus Strength Feca is currently the most popular and arguably the strongest one. It doesn't rely solely on Strength tho, it more focuses on MP and AP removal whilst being Strength and doing some Earth and Neutral damage. The Dofus Touch Str Feca is not very good.
Agility. The Agility Feca is mid ranged and has some unique spells though not very good ones other than positioning. Agi Feca is solid when you're omni, otherwise not worth it to go Agi.
 Chance. The Chance Feca is really good, with a variety of high ranged Chance spells you can hit your foe from far away while keeping yourself and your allies safe. The Chance Feca is really strong in both Dofus versions, though I'd avoid Cha Feca on Touch if you plan to farm Gobball Dungeon for kamas. This is primarily where Int Feca excels.

Dofus (PC)

Full Intelligence Feca

Your main goal should be getting Vitality overmaged on all the pieces unless stated otherwise.

Low Level (~60)

Caracap gives Feca the much needed AP.

Turkocape for 5 MP or take Hooded cloak if you want more damage.

Cherry Amublop.

Cherry Bloopts.

Cherry Blop Belt.

Cherry Blop Ring.

Sponghield or Treechnid Shield.

Kings' Staff, replace for God Rod if you want more AP but note that the God Rod is a lot more expensive.

Omerta Ring, replace this for a Gelano if you want more AP.
The best Trophies for the Low level Intelligence Feca set: Minor Scholar, Minor Survivor, Twitcher, Silver and Cawwot dofus. The best mount for this set is a Seemyool.

Mid level (90~110)

The Mid level set should last you for quite some time therefore it's worth the investment, getting a Vitality overmaged Limbo Wand now will cut some costs from the latter sets. With this set you should be tanky enough for Kolo fights whilst doing some damage as well.
Upgrade your Cherry Blop Set into the Royall Morello Cherry Blop version.

Feudala Hat.

Feudala Cloak.

Gelano, get a MP one if you can afford to. Then you can use Jackanapes for 11 AP.

Treechnid Shield.

Limbo Wand.
The best Trophies for the Mid level Intelligence Feca set: Scholar, Survivor, Dokoko, Dynamo, Twitcher and Jackanapes if you get a MP Gelano. The best Petsmountfor this set is a Brulay if you want the damage, otherwise go with a Seemyool if you can't afford a MP Gelano.

High level (160~199)

This set will serve you until the End game, MP Gelano is quite cheap nowadays because it's much easier to mage one due to MP runes being dirt cheap.

MP Gelano if you want 6 MP, otherwise Vitality.

Limbo Wand.

Inn Shield.

Drhossil Boots.

Nekochief, BiS.

Obsidemon Cloak.

Obsidemon Ring.

Pants Fordamemory.

Ush's Collar.
The best Trophies for the High level Intelligence Feca set: Shaker, Nomad, Major Intellectual, Major Survivor, Major Scholar and Crimson Dofus. The best mount is a Seemyool but you can also go with the Brulay.

End game (lvl 200)

This set focuses on Int Feca more as a damage dealer than a support, if you want to be tankier swap the Nomarow items.

Belteen, BiS. If you can't afford it, buy Jolly Good Belt.

Queen of Fate Boots.

Steelymace. Expensive, can be swapped for Shorpoon.

Merdiodon Cloak. Gives you 11th AP. It is pretty much BiS.

Nomarow Helmet.

Nomarow Ring.

Hairsh Bracelet. MP Exo'd will give you 6th MP.

Four-Leaf Shield. BiS for any Crit ranged build, if you decide to drop the Nomarow items go with Stalak Shield.

Treadfast Amulet, IMO really good because we're Crit.
Trophies: Crimson Dofus, Turquoise Dofus, Major Intellectual, Major Scholar, Major Vigour and Major Survivor. Best mount is definitely a Seemyool.

Omni Feca

Multi Element Feca is not really viable before End game due to gear limitations. I ran this lvl 200 set and it's absolutely nuts. The whole build focuses around the Blord Warrior's Cursed Sword. You shield yourself, put the AP reduction glyph on the enemy and smack them with the Sword. With this set having 50% Crit on the sword and a ton of Critical Damage it can hit 4000 on a Crit. Note though that this set is EXTREMELY expensive, you'll need about 50mk at the very least to pull this off.

End game (lvl 200)

The Dorado is BiS for the Omni Feca.

Dofusteuse is very expensive but it pays off.

Blord Warrior's Cursed Sword is the real monster of this set!

Captain Amakna Shield is needed because it gives Critical Chance our Blord Warrior's Cursed Sword desperately needs.

Hairsh Bracelet needs to be AP exo'd if you want 11 AP.

Nomarrow Ring.

Treadfast Amulet.

Cycloid Boots give a lot of Stats and Damages, these are great boots.

Treadfast Belt.
The best Trophies for the End game Omni Feca set: Crimson Dofus, Turquoise Dofus, Emerald Dofus, Shaker, Nomad, Major Vigour. The best mount is a Seemyool because it gives MP and Resists!

Strength AP reduction Feca

The Strength AP rape Feca is extremely tanky and able to get an enemy down to 4 AP in most cases. This is an extremely powerful PvP set but is quite useless in any PvM environment and it's quite boring to play IMO.

End game (lvl 200)

Dark Court Boots.

Dark Court Belt.

Seven Years Bad Luck is BiS for this build.

Crustic Ring, you will need 2 of these. And yes, you can wear two of them at once.

Lavaxe is a great weapon but very expensive. If you can't afford it there are cheaper alternatives.

Koutolou Mask is BiS for this build and really any other End game 11 AP Str set.

Inky Veil is expensive but worth it because of the crazy Stats.

Treadfast Amulet, it is REALLY important to get -Critical Resist maged off it because you'll get rekt in Close Combat vs anyone who Crits (basically everyone in lvl 200 fights).
The best Trophies for the End game STR AP Reduction Feca set: Shaker, Nomad, Major Vigour (can replace for Crimson Dofus), Major Maniac, Major Obstructor and Major Stunner. A Seemyool is awesome for this setup.

Dofus Touch

Full Intelligence Feca

Focus on Vita overmage on all items because more survivability means more damage.

Low Level (~60)

Same set as the PC level 60 version, just change the Seemyool for any type of Orchid Dragoturkey, preferably Emerald and Orchid Dragoturkey.

Mid level (90~110)

Same set as the PC level 90-110 version, change Seemyool for Emerald and Orchid Dragoturkey.

High level (160~199)

Without the Shaker and Nomad on Touch version there is really no reason not to combine as much Set pieces as you can, therefore we run the Obsidemon Set pieces. You can replace the Nekochief for an Obsidemon hat although I wouldn't recommend it because the Nekochief gives a lot more Stats

Pants Fordamemory. BiS.

Obsidemon Ring.

Nekochief.

Gelano. Mp exo preferred.

Limbo Wand.

Obsidemon Amulet.

Obsidemon Boots.

Obsidemon Cloak.
The best Trophies for the High level Intelligence Dofus Touch Feca set: Major Scholar, Major Survivor, Jackanapes (for 12 AP), Dokoko, Crimson Dofus and Turquoise Dofus. The best Mount for this set is an Emerald and Plum/Orchid Dragoturkey or a 90 Int pet.

Full Chance Feca

As always, focus on Vitality overmaged gear pieces.

Low Level (~60)

This set is quite powerful for the Low levels, if you don't like the downsides of a Blop set feel free to run another set.

Indigo Amublop.

Indigo Bloopts.

Indigo Blop Ring.

Indigo Blop Belt.

Gelano, preferably MP exo.

Turkocape.

Akwadala Staff is the best and cheapest until Axel.

Caracape.
The best Trophies for the Low level Chance Dofus Touch Feca set: Minor Player, Minor Survivor, Twitcher, Cawwot Dofus and fill with any other useful stuff. The best Mount for this set is an Indigo and Emerald Dragoturkey

Mid level (90~110)

The Mid level set scraps on your Blop set to cut on the costs of the new set. You can always get something else if you don't like the Royal Indigo Blop set.
Upgrade your Indigo Blop Set into the Royal Indigo Blop set.

Keep using Turkocape if you want more MP or replace it for a Bwork Chief Cloak.

Caracap gives you the AP chance Cra desperately needs.

Gelano, can get 6th MP from exo.

Axel is the BiS weapon for any Chance character up to end game pretty much.
The best Trophies for the Mid level Chance Dofus Touch Feca set: Player, Survivor, Jackanapes (If you want 12 AP), Cawwot Dofus (more wisdom = more mp reduction), Crimson Dofus, fill the last two spots with whatever you'd like. The best mount for this set is Emerald and Indigo Dragoturkey if you're not at 6 MP already.

High level (160~199)

This set is focused on Chance but also provides you with some Intelligence making you an effective Cha/Int Hybrid. Often times enemies that have high Water resistance won't have high Fire resistance, allowing you to exploit it.

Minotot Necklace.

The Maidartes. BiS boots at this level for any Chance character.

Minotot Belt.

Minotot Cloak.

Minotot Helmet.

Gelano. Preferable MP Exo'd.

Axel, still your best weapon due to it giving one AP.

Minotot Bracelet.
The best Trophies for the High level Chance Dofus Touch Feca set: Major Powerhouse, Major Player, Major Survivor, Crimson Dofus, Jackanapes and Emerald Dofus. The best Mount for this set is a Kwyness if you need the AP, otherwise any Indigo/Emerald mix will do.