Armor of Agathys 5e Guide: What is Armor of Agathys?

Armor of Agathys is a 1st-level abjuration spell on the Warlock spell list. It has a casting time of 1 action, a range of self, a duration of 1 hour, and verbal, somatic, and material components. When you cast the spell, a magical aura of protective frost encases you. For an hour, you gain five temporary hit points. If someone hits you with a melee attack while you have any of these temporary hit points, they take five cold damage. 

Because Armor of Agathys has a casting time of 1 action and lasts 1 hour with no concentration, it is often best to cast this spell outside of combat. If you are entering an area in which you expect to be fighting or if you have a moment to prepare before a battle, cast this spell immediately.

I have played in, and DM’d situations where the warlock’s first turn is wasted setting this spell up. Unless you are ambushed in an area that you didn’t even expect to be dangerous, you should have already cast this spell. Welcome to a Armor of Agathys 5e Guide.

At Higher Levels

While this spell is good when cast at 1st level, it begins to shine when cast using higher spell slots. When upcast, this spell gives you five additional temporary hit points and deals five additional points of cold damage per level of the spell.

If only one of these numbers were to increase, the spell would be fine, but since both the temporary hit points and the retributive cold damage increase with spell level, Armor of Agathys is one of the best spells to upcast.

If Armor of Agathys is cast using a 3rd level spell slot, you gain 15 temporary hit points. Any creature that hits you with a melee attack takes 15 cold damage.

For example, a creature deals ten points of damage to you and takes 15 cold damage themselves.

Since you still have five temporary hit points, when they attack a second time, they take another 15 points of cold damage. They’ve now taken 30 points of cold damage on their turn.

How to Get Armor of Agathys

There are multiple ways to access Armor of Agathys.

1. 1. Be a Warlock. Armor of Agathys is on the warlock spell list. If you have at least one level in warlock, you gain access to this spell.
   2. Be a Mark of Warding Dwarf. The Mark of Warding Dwarf is a racial option from Eberron: Rising from the Last War. If you take this option and play as any class with spellcasting or pact magic, you gain access to Armor of Agathys. Since this racial option is setting-specific, talk with your DM about it. In my homebrew world, dragonmarks don’t exist, so I don’t allow this option at my table.
   3. Be a Clockwork Soul Sorcerer. This is a sorcerer subclass from Tasha’s Cauldron of Everything. Your Clockwork Magic feature gives you access to abjuration and transmutation spells from the sorcerer, warlock, and wizard spell lists.
   4. Be a Conquest Paladin. This is a paladin subclass that has Armor of Agathys on its spell list. Since paladins are half-casters, you get access to it at 3rd level, much later than warlocks and sorcerers. 
   5. Magical Secrets. This is a bard ability at level 10 (level 6 for lore bards) that gives you access to any spell in the game. Armor of Agathys is a good spell, but in this case, it is competing with every 2nd, 3rd, 4th and 5th spell in the game. Many bards will find a better use of magical secrets than Armor of Agathys, but it’s possible to access it in this way.

There are additional ways to gain access to this spell. However, they are not as effective in practice.

You can gain access to this spell through the Magic Initiate feat. This feat gives you access to a 1st level spell from the class spell list you choose. If you pick warlock, you can access it. The problem is that this feat does not allow you to cast the spell using your spell slots. This means that you can only cast it once per day at its lowest level.

Similarly, you can play a Levistus Tiefling from Mordenkainen’s Tome of Foes, who can cast Armor of Agathys once per day as a 2nd level spell. While this is better than Magic Initiate since it’s upcast to 2nd level, it’s still too limited to be worthwhile.

Optimizing Armor of Agathys

In order to make the most of this spell, it is often useful to combine it with other class features and spells. Warlocks most commonly use this spell, and it has some great synergy with other warlock abilities.

Armor of Agathys for a Warlock

A hexblade warlock tends to get the most out of this spell as a warlock. It is a great defensive boost that deters enemies from ever attacking you. As a hexblade warlock, you spend your time in melee with enemies, drawing their fire.

Conversely, I have played as a genie pact warlock who stays out of the fray and uses Eldritch Blast to grate people along Spike Growth. While Armor of Agathys is a great spell, my genie warlock is not getting the same usage from it as a melee character would. Consider how often this spell will be the best use of your limited spell slots.

This spell also combines well with other defensive spells like Shadow of Moil, which heavily obscures you. This makes you hard to hit and deals damage if you are hit.

The Abjuration Wizard

The most effective use of Armor of Agathys is by the Abjuration Wizard. You can access the spell from one level of warlock or being a Mark of Warding Dwarf from Eberron. An abjuration wizard gains the feature Arcane Ward, which functions as a protective shield that takes damage instead of you.

This means that if you have cast Armor of Agathys on yourself and have your Arcane Ward up, a creature that hits you with a melee attack will take the cold damage from your armor. However, the Arcane Ward will take the damage first before even reducing your temporary hit points. This increases the number of attacks that will trigger damage by adding a protective layer that takes damage before your armor does.

To fully exploit this interaction, pick up the Armor of Shadows eldritch invocation, and you will be able to cast Mage Armor at will. Not only does this benefit your AC, but every time you cast it, it refills the hit points of your Arcane Ward, allowing you to get it to the full after every battle.

Read here to learn more about the Abjuration Wizard.

Armor of Agathys and Damage Reduction

Damage reduction is important to make the most of Armor of Agathys. Since the retributive damage is only dealt on a hit, increasing AC—while a good idea—does not directly impact your Armor of Agathys. Instead, having abilities that reduce damage on a hit is important to prolonging the number of hits you take before your armor is fully destroyed.

Since Armor of Agathys is triggered on a melee attack, most of the time, the damage being dealt will be physical: bludgeoning, piercing and slashing. Some high-level abilities give you damage resistance, like the war cleric’s 17th-level ability. Some more accessible ways to reduce damage include:

• Blade Ward. This cantrip gives you resistance to physical damage from weapon attacks. If you’re an earth genasi, you can also cast this spell a few times per day using a bonus action. The downside is that most of the time, it is using up a step. It can be helpful when severely outnumbered.
• Barbarian’s Rage. While you gain resistance to physical damage (or all damage except psychic as a Bear Totem Barbarian), the massive downside is that you can’t cast or concentrate on spells. 
• Heavy Armor Master. This feat reduces the amount of physical damage by 3 per attack. You will need to find a way to get heavy armor on your character build.
• Absorb Elements. While this is only useful for elemental damage, this 1st level spell is an easy way to grant yourself damage to an incoming attack as a reaction.
• Stoneskin. This 4th level spell gives the target resistance to non-magical physical damage. This is a useful way to halve the damage dealt to you, but it won’t work if enemies make magical attacks.
• Guardian Coil. This fathomless warlock feature lets you reduce the damage done to you or an ally within 10 feet by between 1d8 and 2d8, depending on your level.
• Bastion of Law. This clockwork soul sorcerer feature lets you reduce damage taken by up to 5d8. However, the cost of this ability is relatively high at up to 5 sorcery points.
• Fiendish Resilience. This fiend warlock feature lets you choose one damage type to be resistant to each day. Choose either piercing or slashing as they are the most common types of physical damage dealt.
• Full of Stars. While you get this quite late in the game, this 14th-level ability gives you resistance to all physical damage, including from magical sources.

While you may not be a fighter or barbarian using Armor of Agathys, these features allow an ally to reduce the damage done to you.

• Interception Fighting Style. A fighter or other ally who gains this fighting style through a feat can reduce the damage dealt to someone within 5 feet of them by 1d10+ their proficiency bonus.
• Protective Field. This psi warrior fighter feature lets them reduce the damage dealt to someone within 30 feet by between 1d6 and 1d12, depending on their level.
• Spirit Shield. This ancestral guardian barbarian feature lets them reduce the damage dealt to someone within 30 feet of them by between 2d6 and 4d6, depending on their level.

Armor of Agathys and Find Steed

If you have a steed from the spells Find Steed or Find Greater Steed, you can combine this with Armor of Agathys to grant your steed temporary hit points as well. These spells say that while mounted on your steed, you can make a spell you cast that targets only you target your steed as well. This effectively doubles the number of temporary hit points and damage that the spell can deal, which makes it a great combination.

Armor of Agathys and Find Familiar

While casting Armor of Agathys on yourself can also affect your steed, it does not affect your familiarity. The rules for Find Familiar specify you can cast spells with a range of touch through your familiar, but this is not the same as targeting your familiar with a spell.

Armor of Agathys and Illusions

When combined with illusory duplicates of yourself, such as the spell Mirror Image or the trickery cleric feature Invoke Duplicity, Armor of Agathys does not give temporary hit points to your duplicates.

In the case of Mirror Image, the spell specifies that your duplicates are destroyed if they are hit with an attack. They do not have any hit points. Similarly, a trickery cleric’s duplicate is an illusion and does not take damage and cannot be hit with an attack.

Armor of Agathys and Echo Knight

If you cast Armor of Agathys and then manifest an echo of yourself as an Echo Knight fighter, it is summoned with the statistics given by the feature and does not gain the benefits of any spells you may have cast on you when you manifest it. After your echo has been summoned, it is considered an object and cannot benefit from this spell.

Armor of Agathys and Metamagic

Armor of Agathys can be influenced by a sorcerer’s metamagic. 

• Careful Spell. Not relevant as there’s no saving throw.
• Distant Spell. Not relevant as the range is Self.
• Empowered Spell. Not relevant as there is no damage roll when dealing damage.
• Extended Spell. Spend one sorcery point to make this spell last 2 hours instead of 1. This is a good use of a sorcery point if you’re unsure how long you need the armor for.
• Heightened Spell. Not relevant as there’s no saving throw.
• Quickened Spell. Spend two sorcery points to cast as a bonus action. This is useful if you get ambushed and don’t already have the spell active.
• Seeking Spell. Not relevant as there’s no attack roll.
• Subtle Spell. Unlikely to be useful. This option is most beneficial to not be counterspell or to cast a spell undetected in social situations. Since you’re covering yourself in frost, which is, most likely, visible, it’s hard to determine how subtle this spell can really be.
• Transmuted Spell. Spend one sorcery point to change the damage type. Useful if you think your enemies may resist cold damage. Acid and thunder are probably your most effective options. This is also a great option if you’re after a certain aesthetic.
• Twinned Spell. Unfortunately, this option doesn’t work on spells with a range of Self, so Armor of Agathys cannot be twinned.

F.A.Q.

Summary

Armor of Agathys is a great defensive spell primarily available to warlocks but accessible via a few other options. As a 1st level spell, it’s a great way of defending yourself on the off chance an enemy gets through to where you are. For melee warlocks like hexblades, it becomes a great source of both defense and offense. This spell should be cast ahead of time as you prepare for battle or venture into dangerous areas so that you don’t waste an entire turn casting it.

The spell scales incredibly well as both the temporary hit points and damage dealt increase by 5 per level. For any caster, this is a great use of a higher-level spell slot at every tier of play. Armor of Agathys works very well when combined with sources of damage reduction like resistance. This spell does not increase your AC despite having “armor” in the name, so look for other ways of defending yourself and enjoy the thrill of taking damage and telling your DM that they’re going to take some too.

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Ethan Scaife

Ethan brings an extensive understanding of D&D game mechanics, storytelling, how to operate the game, and how to optimize playing! He's created many D&D game guides and will always provide the best advice, making sure to scour the source material and shares it all with us here!

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