Gear Review
It seems the most logical conclusion at this current time that a pure heavy attack damage setup for pretty much all classes ends up in a medium armor setup with Storm Master and the heavy armor set Sergeant's Mail in the form of jewelry and weapon.
It also helps that the main item sets are very easily farmable by players of any level!
With Oakensoul as a Mythic item that restricts other Mythics from being used and also restricting the usage of a second skill bar, we don't have too many options in terms of set availability and also makes us resort to a 1x bonus set such as Slimecraw's 1x Critical Chance bonus.
After some testing on both the raid dummies and in content (also based on previous testing with a different iteration of Oakensoul), it doesn't seem the Berserker enchant (Weapon/Spell Damage increase) will outperform either Poison or Flame Damage enchantments on the Lightning Staff.
Jewelry enchantments can be primarily Weapon or Spell Damage glyphs as either glyph gives both Weapon and Spell Damage, however you will get an extra 30 additional Stamina Recovery with Weapon Damage glyphs for jewelry or 30 additional Magicka Recovery with Spell Damage (assuming gold).
An alternative body setup can be 5x Noble Duelist's Silk or 5x Order's Wrath instead of Storm Master for solo instances/arenas or 4 man content!
Skills Review
We experimented with a few different spammables and found Writhing Runeblades to be the most consistent semi-spammable for this heavy attack build that also generates the 3 Crux we need as Arcanists to empower our other damage skill.
While Cephaliarch's Flail is used as the semi-spammable for a 2-bar Arcanist DPS setup, it didn't yield favorable results on this build where most of the damage is coming from our burst damage Ultimate and heavy attack channeling.
We opted for Tentacular Dread as the debuff and burst damage (at 3 Crux) instead due to its higher debuff value compared to Cephaliarch's Flail.
Barbed Trap is still one of the strongest single target Damage over Time skills in the game and provides Hemorrhaging.
Fulminating Rune is our main AOE based Damage over Time skill while Inspired Scholarship is a long running to amp up our Arcanist skills with some passive damage. It also gives us Major Brutality and Sorcery in solo instances.
Lastly, Languid Eye makes up a huge chunk of our burst damage especially when lined up while we channel our Heavy Attacks on Off Balanced targets with DoTs rolling.
Rotation
Your opening burst rotation (ideally with 3 Crux up) will consist of first casting Inspired Scholarship, casting Barbed Trap, applying Tentacular Dread to target followed by Fulminating Rune then immediately casting Languid Eye into a channeled heavy attack.
For the most part, you will weave Writhing Runeblades with Heavy Attacks and keep up your DoTs / other abilities as best as possible. It's crucial to keep up Tentacular Dread's unique Damage Taken debuff on target and to only cast it when you have 3 Crux.
Tentacular Dread cast is preferred over using another cast of Writhing Runeblades once you have 3 Crux up.
While Languid Eye being used timed with Off Balance is ideal, it may be better to use it even when the target's not Off Balanced due to the amount of damage it gives.
Craft
Warfare
Fitness
Champion Points Review
Celerity is important to help you move out of danger as you channel heavy attacks. Bastion is a flex slottable, meaning you can slot something else you need if not casting a shield, such as Expert Evasion for a free Roll Dodge.
With seven pieces of Medium Armor and Minor Force coupled with the Arcanist passives it isn't really necessary to run Backstabber nor Fighting Finesse in organized group settings.
Introduction
Many people have asked if a heavy attack Arcanist is viable. It certainly is but it has its own challenges unique to the class itself when it comes to a heavy attack spec. Due to the fact that the Arcanist's Fatecarver skill makes up a huge chunk (~42%) of its DPS, substituting the skill out for channeled heavy attacking makes the already DPS-fluctuating class a little bit more difficult to maintain.
The usage of Fatecarver in combination with a heavy attack spec doesn't pan out well either as most of your damage as a heavy attack build comes from your item sets and the actual action of heavy attacking. So a 5+ Global Cooldown (GCD) Fatecarver skill means you essentially lose out on damage.
This build can be used for a variety of content including overland, solo Arenas such as Veteran Maelstrom Arena & Vateshran Hollow, veteran dungeons and Veteran Trials.
Recommended race: Altmer (High Elf) or Dunmer (Dark Elf); for solo or 4-man content Khajiit will have an advantage.
Recommended food will be a bi-stat Health and Magicka food. For parsing or for fights where you don't need that extra health, you can use purely single-stat Max Magicka food! For soloing veteran dungeons, you may need to invest into a tri-stat food (Max Health, Max Stamina, Magicka)!
Recommended Mundus will be The Thief (for group content like Trials) or The Lover (for solo content and overland).
Potions can be your basic tri-stat restoration potions, however if you'd like to invest further into the build, you could go with Resistance Potions that restore 9206 Health immediately & gives Major Fortitude (30% Health Recovery), grants a unique 5280 Spell and Physical Resistances!
You should have about 25,000 resistances, making you basically a tank with around 30,000 Health (includes Minor Toughness if in group with a Warden).
The potion can be made using the following reagents: Mudcrab Chitin, Mountain Flower, Bugloss