Gear Review
To maximize our stat gains, we'll be going with the traditional 5-1-1 setup this means 5x Heavy Armor, 1x Medium Armor and 1x Light Armor. The monster set of choice will be Thurvokun which has an effective uptime of 50% that deals not just Disease Damage every second/tick but also inflicts Minor Maim onto anything in the growing AoE. Note that the damage scales off of your Max Health which you have plenty of and this can be of some little help towards group DPS.
Your primary 5x set will be Dragon's Defilement, a very powerful tanking set that has an effective uptime of 100% should you keep taking melee damage on cooldown. As you won't be using Pierce Armor nor are you a Templar, you will need to provide Minor Breach which is a significant source of Armor Penetration for your group DPS.
Your secondary 5x set will be Brands of the Imperium which grants you and others within 8 meters of you a massive damage shield for 6 seconds and has an effective uptime of 50% every time you take any damage.
The combination of Thurvokun, Dragon's Defilement and the Necromancer class toolkit makes this build quite an AoE intensive build that strongly debuffs and buffs everything around you. The safety nets of the stats and item sets (along with weapons such as the Frost Staff which provides projectile shields and additional Magicka sustain from one of the Destruction Staff passives) of this build will more than likely help quite a lot of tanks with harder content.
The Decisive one hander is self-explanatory as Ultimate gain is quite nice for generally any build. The Infused Shield is solely there to boost the Health stat on the frontbar which will help in times where you don't Block at all. The Hardening or Shield enchantment on the one hander will stack with Imperium and be kept up when the set is on cooldown helping you gain a very very slight gain in damage mitigation.
While enchantments are usually preference, you can't go wrong with primarily Health enchantments on all body pieces as you're maximizing Health in order to take advantage of the healing from the Necromancer skill Scythe and the emergency Ultimate Bone Goliath which adds quite a bit of Health.
Due to the block cost calculations with Sturdy, even without allocating much into Stamina your stamina sustain should be fine. The only worrisome thing would be your Magicka pool. Typically Necromancer tanks on all levels can suffer from Magicka sustain issues which can be circumvented with not overcasting abilities, knowing when to cast those skills and building stats for Magicka sustain such as putting Magicka Recovery enchants on jewelry as shown above and using the Atronach Mundus Stone.
You will note that instead of the typical Crusher enchantment, we do have a Prismatic Onslaught on the infused Frost Staff, this enchantment is quite strong at giving a ridiculous amount of sustain every 4 seconds. In addition to the Stamina and Magicka, it also offers a relatively higher Health return as well which is basically free Health Recovery/Healing every 4 seconds and can be kept up with an Infused trait 100% of the time.
Skills Review
Silver Leash is going to be your primary Pull ability to use in most trash encounters. While Beckoning Armor can passively Pull adds during a fight, it can also proc the Pull even on bosses so it isn't too reliable. Silver Leashing things will be much faster and many will be worried about the Stamina sustain as you need it for Blocking, Roll Dodging and Breaking Free if need be. However since you have quite the large Health pool upwards of 50,000+ you won't need to worry about Block casting the Silver Leash at all in pretty much all trash encounters.
Inner Rage is going to be your primary - and only - Taunt. Dragon's Defilement may provide Minor Breach but what about Major Breach? This can be compensated by keeping up the long duration of Unnerving Boneyard which grants Major Breach on anything inside of it whether it's a boss or a pack of mobs. While Inner Beast - the Stamina morph - is an option, you may need to watch your Stamina sustain a bit more during boss fights.
For Deaden Pain, this can be preference as Necrotic Potency grants more Ultimate gain. Deaden Pain's Major Protection can be quite nice to have for specific instances so it's up to you while Necrotic Potency gives you faster Ultimate for you to cast a Horn or Goliath.
Empowering Grasp is quite optional as it consumes quite a bit of Magicka and may not be necessary for a large portion of any dungeon, DLC or otherwise since most DPS don't really Light Attack during trash fights and instead focus on AoEs unless there are elite adds that you need them to focus for whatever reason.
As a flex slot, you can use Heroic Slash as it generates Ultimate through Minor Heroism or any other skill you may need to slot as utility for your group members such as Overflowing Altar or Resolving/Echoing Vigor as a Stamina-based healing option. Braided Tether, Mortal Coil or Mystic Siphon are solid options or even one of the Necromancer's AoE heal morphs. Pretty much anything that you need goes if you need more skill slots starting with Empowering Grasp.
Hungry Scythe is your primary healing ability, it's a very cheap Magicka-cost heal and scales off of your Max Health which is quite a bit of healing on this build.
Your frontbar Ultimate will be Ravenous Goliath. You're simply invincible against most mechanics and bosses. Far longer in duration than the Dragonknight's Magma Shell, Ravenous Goliath is your emergency Ultimate to use should you need to buy more time or survive or gain resources by Heavy Attacking. Expect to see upwards of 80,000+ Health.
Agony Totem is also a flex slot and can be exchanged for whatever skill you may need such as Elemental Drain if the group needs it or a different utility/selfish skill. It is quite nice to use as a guaranteed Minor Vulnerability proc and AoE Crowd-Control skill for trash encounters however but it is costly in terms of Magicka and must be used wisely.
Blockade of Frost as mentioned under the Gear Review is meant to not only offer yourself and others a large projectile shield or keep up your Prismatic Onslaught enchantment but also to offer you free Magicka sustain which you will need as a Necromancer tank through the Destruction Staff passive Destruction Expert which lets you restore 1800 Magicka PER FROST SHIELD on every person including yourself (occurring once every 10 seconds should they absorb any ranged projectile damage.
Craft
Warfare
Fitness
Beckoning Armor is your main source of Major Resolve for boosting your Physical and Spell Resistances but can sometimes be a nice passive Pull on a random add. Upon recasting this or Spirit Guardian at half or less than half of its duration you can get early corpses to use Deaden Pain/Necrotic Potency on.
Spirit Guardian is a non-negotiable skill to absolutely have. The mitigation offered from it in conjunction with other passives from the Necromancer toolkit that mitigates damage in addition to the available Champion Points Slottables and Perks make it too good for living in almost any 4 man content encounter. It's a free heal for yourself or a group member and just like Beckoning Armor is a free corpse to use your abilities on.
As your backbar Ultimate, Aggressive Horn is ideally what you want to cast over Goliath to give your group DPS Major Force and everybody including yourself an additional 10% Max Stamina and Max Magicka.
Champion Points Review
The four typical Warfare Slottables for most tanks including the Corruption will be Ironclad, Unassailable, Enduring Resolve and Duelist's Rebuff as these cover pretty much all sources of incoming damage in The Elder Scrolls Online.
Fitness Slottables will include Bracing Anchor (Block mitigation), Soothing Shield (consistent healing from Blocking attacks), Sustained by Suffering (added sustain from being debuffed, the more debuffs the better) and Boundless Vitality (more Health).
Introduction (Update 32, Deadlands)
The Corruption tank build makes its return from post-Greymoor to continue the focus on Necromancer tanking four man content on Normal, Veteran and Veteran Hard Mode levels (Dungeons & Arenas).
This build is NOT recommended to take to Veteran Trials. Note that any combination of Defiled Dragon and Imperium can work so long as both five piece sets are active on both bars so don't feel pressured to farm either of the two dungeons they drop from for the specific pieces outlined in the gear setup below!
Corruption has an emphasis on providing crowd control, self survival, group survivability, group utility and increasing your group's DPS via Penetration.
The intent of this build is to never die while still providing the basic fundamentals of tanking in ESO (taunting, debuffing, buffing) at an accessible level.
For a beginner's guide to tanking in The Elder Scrolls Online, you can refer to this guide.
Recommended Races for this build are Imperial, Nord, Argonian, Breton and Redguard. For race recommendations you can refer to this video.
Recommended potion for this build is an Essence of Health (tri-stat).
Recommended food for this build is Bewitched Sugar Skulls or Orzorga's Red Frothgar if you switch to Block Cost/Stamina Cost Reduction glyphs on jewelry and Prismatic enchantments on every body piece.
Recommended Mundus Stone is The Atronach or The Lord.
For gameplay and the video showcasing this build, refer to the video above.