Arcanist Healer Build
Arcanist healer builds are some of the best in the game, capable of providing a massive degree of healing power while also supplying the whole team with very powerful buffs that are difficult to come by. Arcanists can cast shields on allies and protect themselves from a lot of punishment, making them especially good at staying alive in this role.
Gear Sets
Jorvuld's Guidance: This set works great on any class that provides a good amount of major and minor buffs or shields, meaning it is perfect for an Arcanist. You can find this set in Scalecaller Peak.
Roaring Opportunist: Synergizing perfectly with Jorvuld's Guidance, Roaring Opportunist offers the incredibly valuable Major Slayer buff. This increases significantly with the amount of max Magicka we have, and increases further with Jorvuld's Guidance. You can get this set from Kyne's Aegis.
Symphony of Blades: This is hands down one of the absolute best sets to run on any healer, providing an absolute ton of resources back to your whole team regularly. This can be obtained from Depths of Malatar.
Perfected Grand Rejuvenation: Helping further with providing resources back to your group, this set will boost the Stamina and Magicka Recovery of any team member within the AoE by a lot, making it a valuable item. You can get this from Veteran Dragonstar Arena.
Skills
Combat Prayer: A powerful and important AoE skill that applies a heal, Minor Berserk and Minor Resolve to all friendly targets hit. You should use this as your main healing spammable.
Illustrious Healing: This allows for a large amount of healing over time in a wide area, and it is important to keep this up as much as possible.
Radiating Regeneration: Automatic healing on allies no matter where they stand! In 12-man content, you will need to cast this multiple times to hit everyone.
Zena's Empowering Domain: Grants a ton of buffs to all allies in the area. This morph allows the Minor Intellect, Minor Endurance, Minor Fortitude and Minor Courage buffs to persist on allies after they leave the area. In organised, tightly-stacked content, you can use Reconstructive Domain instead.
Rune of the Colorless Pool: Provides the very valuable Minor Vulnerability and Minor Brittle debuffs, which boosts overall DPS a lot.
Gibbering Shelter: Allows you to soak up a lot of damage in a sticky situation, which will also allow your allies to soak up damage when your shield is hit.
Elemental Blockade: FLEX - Supporting AoE debuff skill that can slow enemies, apply Chilled and Brittle to them, and even freeze them in place.
Escalating Runeblades: Your main source of generating Crux, which will empower Tidal Chakram and Cascading Fortune.
Tidal Chakram: Allows you to provide a shield to up to four allies, which is invaluable in intensive content. Can be empowered by consuming Crux to heal allies.
Energy Orb: A moving heal over time in a decently sized area that can be activated by each ally to provide a bunch of resources back to them. Aim this at the tank.
Cascading Fortune: FLEX - An incredibly powerful healing skill to be used in the toughest situations. This can be switched out for more utility if needed.
Aggressive Horn: A classic support ultimate that boosts the damage output of the whole group massively for a long period of time.
Champion Points
Soothing Tide: This perk grants a substantial power boost to your area healing abilities, allowing you to strategically place healing area spells where they are needed most.
Swift Renewal: Healing over time abilities are some of the most common you will use on a healer, and this will boost their healing power substantially.
Hope Infusion: The ability to grant Minor Heroism to allies is a very useful boon to you and your group. Every time you heal an ally below 50% health, you will grant them Minor Heroism for one second per 300 Magicka Recovery that you have.
Enlivening Overflow: Similar to Hope Infusion, you can grant resource recovery to your allies based on how high your Max Magicka is, up to 150.
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.
Rejuvenation: Recoveries are important for every role. For healers, it is essential for keeping your group alive, for tanks, it is the source of most of your buffs and debuffs, for DPS, you can't deal damage with no fuel, and in PvP, no resources means death.
Celerity: Extra movement speed is an amazing boost in all content. In PvE, it helps massively with avoiding nasty mechanics, and in PvP, it allows you to run circles around your opponents.
Mundus Stone
The best Mundus Stone to use on this build is the Thief. Good healers are adepts at stacking up plenty of healing over time so they can focus on individual targets or on buffing instead, and critically healing boosts healing power massively. However, if you have enough critical chance, use the Mage for more max Magicka, or Atronach if you need more recovery.
Food Buff
The Ghastly Eye Bowls food buff is typically the best option for any PvE Magicka character. It offers the best combination of Max Magicka and Magicka Recovery. If you are in content that requires higher health, you can use the Withmother's Potent Brew or Clockwork Citrus Filet if you prefer.
Race
The best race to use for this build is a Breton. This is the best race in ESO for Magicka sustain, but the Argonian is also a good option.
Potion
Spell power potions will offer this build access to the valuable Major Sorcery and Major Prophecy buffs, both of which will boost your healing power by a lot. You also get the much needed Magicka return, and a long boost to your Max Magicka.
Mortality
The benefits of being a Vampire or Werewolf are not worth the drawbacks on this build. Therefore, it is strongly recommended that you remain a Mortal with this build to ensure you don't run into issues.
Notes
Arcanist Healers have some of the strongest raw healing power available at their disposal, and can offer a range of buffs and debuffs to subsidise that. It is important to ensure that healing over time abilities are active on your allies at all times, and that you are managing your Crux generation and expenditure in an efficient way to get the most out of your abilities.