A protective magical force surrounds you, manifesting as a spectral frost that covers you and your gear. You gain 5 temporary hit points for the duration. If a creature hits you with a melee attack while you have these hit points, the creature takes 5 cold damage.
At Higher Levels. When you cast this spell using a spell slot of 2nd level or higher, both the temporary hit points and the cold damage increase by 5 for each slot.
Casting Time: 1 action
Components: V, S, M (a cup of water)
Duration: 1 hour
School: 1st-level abjuration
Player’s Handbook, pg. 215
Armor of Agathys 5e
Who Can Cast Armor of Agathys in 5e?
The following classes have Armor of Agathys on their spell list:
The following subclasses get Armor of Agathys for free:
Paladin (Oath of Conquest) (XGtE 38)
Additionally, Mark of Warding Dwarfs from Eberron: Rising from the Last War campaign setting have Armor of Agathys added to the spell table of their spellcasting class (provided they have one) starting at 1st level (pg. 51).
What Does Armor of Agathys Do in 5e?
Armor of Agathys grants you 5 temporary hit points and causes melee attackers who hit you to take 5 cold damage. The spell lasts for one hour and requires no concentration to maintain.
As long as any temporary hit points from the spell remain on the you, a melee attacker will take full cold damage when they hit you. Once the temporary hit points are gone, melee attackers no longer take any damage when they hit you.
AoA can be upcast for an extra 5 temporary hit points and cold damage per slot level.
What Are the Rules for Armor of Agathys in 5e?
The rules for Armor of Agathys in DnD 5e are as follows:
Armor of Agathys only requires 1 temporary hit point to deal full cold damage. You don’t need to absorb the full damage taken to deal damage, and the damage AoA deals remains constant regardless of the amount of temporary hit points the caster has from the spell. Confirmation from Sage Advice.
Armor of Agathys only deals damage while the caster has the specific temporary hit points from AoA — not any other source. This Sage Advice thread initially cleared up the confusion a bit, but JC really should’ve emphasized one word of his comment — “Armor of Agathys is effective only as long as you have ITS temporary hit points” (my emphasis).
This was also confirmed in the Sage Advice Compendium, which also reminded players that temporary hit points aren’t cumulative, and a player has to decide which temporary hit points effect they would like to benefit from (SAC 16, PHB 198).
So choosing to gain THP from a spell like False Life or an effect like Dark One’s Blessing will prematurely end Armor of Agathys.
A creature cannot die from Armor of Agathys’ damage before dealing damage to the target. Part three of the rules for attacking reads:3. Resolve the attack. You make the attack roll. On a hit, you roll damage, unless the particular attack has rules that specify otherwise. (PHB 194)
In other words, if a player with AoA is hit by a melee attack, the attacker rolls their damage first, deals that damage to the player, and THEN AoA deals damage to the attacker. That AoA damage can totally kill the attacker, but they still landed their attack and dealt damage as normal.
Arcane Ward allows a player to deal Armor of Agathys’ damage even if the temporary hit points aren’t affected by the triggering attack. Arcane Ward is a second-level feature of the Abjuration Wizard subclass that takes damage before the Wizard takes damage (PHB 115).
Arcane Ward takes damage before temporary hit points as well (SAC 7), but since Armor of Agathys is still active and the caster is still being hit, a melee attacker will still take damage from AoA.
Armor of Agathys doesn’t deal damage if the caster is grappled or shoved. As the Sage Advice Compendium points out, an athletics check to grapple or shove someone is not making an attack roll (SAC 10). As such, you cannot be “hit” by this special melee attack, and therefore cannot trigger Armor of Agathys’ damage in response to either.
Mage Armor stacks with Armor of Agathys. Neither require concentration and they’re different spell effects, so they stack just fine.
Armor of Agathys’ damage triggers from melee spell attacks, including Spiritual Weapon.
Fire Shield and Armor of Agathys stack. Fire Shield also deals damage when the caster is hit by a melee attack. Both this spell and Armor of Agathys can be active at the same time and both deal damage in response to the caster being hit by a melee attack.
Mirror Image and Armor of Agathys do not stack. The way the Mirror Image spell works is that your mirror takes a hit instead of you. A requirement of Armor of Agathys is that “a creature hits you” (emphasis mine).
Since it’s not really you being hit, Armor of Agathys’ damage doesn’t trigger when your mirror image is hit.
Does Armor of Agathys disappear? Armor of Agathys only stops dealing cold damage once the temporary hit points granted by the spell run out. Whether or not the “spectral frost” armor remains on the caster for the remainder of the hour is not so clear. If you cast a different spell that grants temporary hit points, then Armor of Agathys ends and disappears (SAC 16).
How Do I Use Armor of Agathys in 5e?
Here are a few ways to get the most out of Armor of Agatyhs at your next DnD session:
Pair with Abjuration Wizard. A popular character build among players is to run an Abjuration Wizard and take a one or two level Warlock multiclass dip to grab Armor of Agathys.
The reason this is so strong is Arcane Ward — the fact that it takes damage before the temporary hit points while still triggering AoA’s cold damage means that you get a lot more mileage out of the offensive nature of Armor of Agathys.
It gets even better if you’re regularly casting abjuration spells in combat and can continuously recharge the duration of your Arcane Ward.
Pair with resistance. Things like Barbarians’ Rage (again, multiclass or feat-dependent), Fiendish Resilience (if you’re The Fiend Warlock subclass), the Stoneskin spell (multiclass or Paladin (Oath of Conquest)-dependent), and Blade Ward cantrip all pair extremely well with AoA, ensuring that you extend the life of AoA’s temporary hit points.
Pair with other damage-reducing effects. Besides straight-up resistance, there are other ways to reduce the amount of incoming damage you take while Armor of Agathys is active.
A Lore Bard’s Cutting Words feature, the Heavy Armor Master feat (PHB 167), and Goliath’s Stone’s Endurance trait (VGtM 109) are examples of different ways to reduce incoming damage while still dealing full AoA damage.
Pair with other retaliatory-damage effects. Spells like Fire Shield stack with Armor of Agathys, and can make you a very dangerous target for melee attackers — so much so that they may think twice about attacking you at all.
Cast it before combat (when possible). This is more of a tactical tip than a strategic one: Armor of Agathys’ casting time is 1 action, so if you’re already in combat, it’s probably not worth casting. Your action would likely be better spent casting a utility spell or just straight up attacking.
AoA lasts for a full hour, so if you’re starting a dungeon dive, get that spectral frost look going right from the get-go.
Pair it with a melee build. The Hexblade subclass and the Pact of the Blade Pact Boon are the natural choices for a Warlock who wants to get the most out of Armor of Agathys. It also works well with multiclassers who like to be in the middle of the fray.
A regular ol’ sit-back-and-spam-Eldritch-Blast-all-day Warlock won’t see nearly as much value from Armor of Agatyhs.
Purposefully trigger opportunity attacks. If you’re feeling especially good about your level of resistances/damage reduction methods, one way to get some level of control over who you damage with Armor of Agathys is to purposefully trigger opportunity attacks.
There’s no guarantee that they’ll take the bait, but it can be a good tactic to create tricky DM decisions.
Stay cool. Hey, the spell does coat you and your gear in spectral frost. That’s gotta help a bit on desert adventures. This is obviously a flavor use of the spell rather than a practical one, but that flavor text ain’t there for nothing — roleplaying is a pillar of the game after all.
Is Armor of Agathys 5e a Good Spell?
Armor of Agathys is a good spell if you optimize your character build a bit around it. Here are the spell’s pros:
Free damage (no rolls)
Triggers on each instance of damage (good against multiattackers)
Great reason for a multiclass dip for some classes/builds
Good for hexblades
And here’s why Armor of Agathys isn’t so great:
Bad in early game, likely only lasting for 1 hit and 1 round of damage
No control over who takes damage
Not good on ranged builds
Requires a bit of optimization to really make it shine
Overall, Armor of Agathys can be very powerful if you plan your build around it, but it’s certainly not an insanely powerful spell on its own.
Armor of Agathys 5e DM Tips
There’s not much to cover for DM’s with Armor of Agathys — follow the rules, be consistent, and you’ll be fine.
There is, however, the question of the spectral frost and what sorts of roleplaying situations that sets up. For example, a deadpan, cold-eyed character might use Armor of Agathys’ visual effect to boost an intimidation check. Or a player might try to deceive a passerby by pretending to be dying of hypothermia, boosting a deception or performance check.
I say allow these extra uses. They’re not likely to come up often, and the fact the spell specifically mentions the visual appearance of the armor means that it should matter in the setting and inform how creatures interact with the caster. Spectral frost armor isn’t something most people see every day, after all.
Simple Armor of Agathys 5e Spell Text
Armor of Agathys: (1st-level abjuration, Self, 1 hour, V/S/M (a cup of water)) +5 temporary hit points. When hit by a melee attack while you have these temporary hit points, the creature takes 5 cold damage | +5 temporary hit points and cold damage per slot level above 1st.