Arcanist Tank Build
Arcanist tank builds maintain incredible survivability and provide very powerful debuffs to enemies that will help your group's damage output massively. Arcanist tanks can also aid the rest of the group with buffs, shields and even healing to help them keep up the damage for longer.
Gear Sets
Archdruid Devyric: This is a great set that gives your group access to Major Vulnerability without relying on having Necromancers present. Even if they are, this can help to bridge the gaps between Glacial Colossus activation. Get this set from Earthen Root Enclave.
Turning Tide: Another great set for access to Major Vulnerability that will allow you to get much better uptime on this powerful debuff. You can get this from Shipwright's Regret.
War Machine: With great uptime on Major Vulnerability, this set combos perfectly for nice uptime on Major Slayer as well, giving your group a total combined DPS output of 20% which is huge. Get this set from Halls of Fabrication.
Puncturing Remedy: This set allows you to boost your resistances and heal yourself without doing anything extra - you only need to use your taunt! You can get this from Dragonstar Arena.
Skills
Runic Sunder: This is an awesome single-target taunt that passively reduces your damage taken while slotted, and will reduce the armor and damage done of the target when used.
Impervious Runeward: Allows you to grant yourself a powerful shield, which is even much stronger for the first second it is used, allowing you to shrug off powerful hits that you see coming.
Heroic Slash: The main use of Heroic Slash is to generate ultimate, which will allow greater uptime on your Saxhleel Champion gear set.
Runeguard of Still Waters: A very efficient skill that provides Minor Resolve to your whole group, Minor Protection to you, an auto-heal if you take too much damage, and an immobilization against your enemies.
Silver Leash: Pull enemies to you to allow for much better battlefield control.
Gibbering Shelter OR Reviving Barrier: Both of these apply a damage mitigation shield to you. Reviving Barrier also applies this to all your allies, whereas Gibbering Shelter requires you to take damage to do this. Gibbering Shelter will grant you extra magicka and stamina recovery through your passives.
Elemental Blockade: Subsidiary crowd control area of effect skill that can slow and immobilize enemies on top of applying the Chilled and Brittle status effects, and also provides a projectile shield to you and your allies.
Rune of the Colorless Pool: This can be used to incapacitate minor enemies if needed, but is primarily used to apply the Minor Vulnerability and Minor Brittle debuffs to bosses.
Reconstructive Domain: Provides extra health, magicka and stamina recovery as well as weapon and spell damage to you and all allies in the area, on top of healing over time.
Razor Caltrops: Provides a snare and the powerful Major Breach to all enemies in a wide area, which is essential to this build.
Frost Clench: Serves as a ranged, magicka-costing taunt that also applies Major Maim and immobilizes the target.
Aggressive Horn: Increases the damage of the entire group by a large amount for a significant amount of time.
Champion Points
Ironclad: This grants you a nice boost to your damage mitigation against direct damage attacks, which is one of the most common that you will encounter in PvE.
Enduring Resolve: Damage over time mitigation is very useful, since it counts for single target DoTs and area DoTs. This means that, in many cases, this will stack with Unassailable.
Duellist's Rebuff: Often stacking with Ironclad to further boost your resistance against single target attacks, this is a useful one for tanks in particular, helping to mitigate the heavy damage coming from bosses.
Unassailable: Helping you to stand in stupid for longer, Unassailable will reduce your damage taken from area attacks, helping towards taking the pressure off the healer.
Boundless Vitality: Every bit of health makes a difference, especially in some of the tougher content that The Elder Scrolls Online has to offer. This will help you bump yours up a little more, increasing your survivability.
Fortified: Similar to Boundless Vitality, one can never have enough resistances, and this will add a little extra to boost your survivability so that you can focus more on the task at hand.
Sustained by Suffering: Gaining the ability to regenerate resources faster when you have negative effects on you is just perfect for a tank, making this a smart choice.
Bracing Anchor: As a tank, you don't need to move that much, but you certainly need to block as much as possible, making this a great addition to your toolkit.
Mundus Stone
Tanks benefit incredibly well from the Atronach Mundus Stone, boosting their Magicka recovery significantly for their very important Magicka-based skills. Preserving Stamina is important, since this will be expended heavily whilst blocking.
Food Buff
Tanks benefit especially well from Orzorga's Smoked Bear Haunch, boosting all recoveries along with Max Health as well. However, it is expensive, so if you need a cost-effect option, use the Bewitched Sugar Skulls, which are also very effective.
Race
The best race to use for this build is a Nord for its higher resistances and ultimate regeneration, but Argonians, Imperials and Bretons are also excellent options for their superior survivability and sustain.
Potion
Tri-restoration potions are generally the best for any tank to run, allowing you to manage your resources perfectly. However, when you are dealing with trash mobs and the like, you won't want to waste them, so carry some trash potions around for the parts that aren't very intense.
Mortality
The Undeath passive can be tempting for tanks, but running a Vampire on all but highly specialised and rather inefficient builds is a bad idea. The amount of fire damage found in PvE content, and the high increase to standard skill costs, will make running Vampire on a PvE tank a liability.
Notes
Arcanist Tanks are currently some of the most powerful around, with access to some amazing survivability tools along with very useful group buffs and enemy debuffs. With an Arcanist Tank in particular, you must ensure that you are managing your resources effectively, as keeping up all of those valuable buffs and debuffs is rough on sustain. Make sure you are heavy attacking, activating synergies and using potions to subsidise this.