Dim, greenish light spreads within a 30-foot-radius sphere centered on a point you choose within range. The light spreads around corners, and it lasts until the spell ends.
When a creature moves into the spell’s area for the first time on a turn or starts its turn there, that creature must succeed on a Constitution saving throw or take 4d10 radiant damage, and it suffers one level of exhaustion and emits a dim, greenish light in a 5-foot radius. This light makes it impossible for the creature to benefit from being invisible. The light and any levels of exhaustion caused by this spell go away when the spell ends.
Casting Time: 1 action
Range: 120 feet
Components: V, S
Duration: Concentration, up to 10 minutes
School: 4th-level evocation
Who can cast Sickening Radiance? Sorcerers, Warlocks, and Wizards have Sickening Radiance on their class spell lists.
Xanathar’s Guide to Everything, pg. 164-5
Sickening Radiance 5e
Sickening Radiance is one of the dirtiest spells that 5e has to offer. Literally, it’s like DnD’s version of a dirty bomb, with irradiated gunk that comes with all sorts of nasty side effects, including being the only spell that causes exhaustion in DnD 5e.
And it combines extraordinarily well with some other spells and effects. I’ll go over how Sickening Radiance works, cover the most common rules questions that come up, and talk about popular strategies for getting the most mileage out of this 4th-level spell.
How Does Sickening Radiance Work in 5e?
Sickening Radiance causes 4d10 (22 average) radiant damage, causes +1 level of exhaustion, and causes a dim light to be emitted that negates invisibility from any creature in a 30-foot-radius sphere who fails a Constitution saving throw. It wraps around corners, meaning it can even affect creatures who are out of the caster’s direct line of sight.
Sickening Radiance lasts for up to 10 minutes (concentration permitting) and affects all creatures; allies and enemies alike. If a creature passes its saving throw, no negative effects take place: no damage, no anti-invisibility effect, and no exhaustion.
— Jeremy Crawford (@JeremyECrawford) November 10, 2017
But if it lands even once, the anti-invisibility effect and exhaustion level(s) remain until the spell ends (either by concentration being broken or the duration ending).
The effects of Sickening Radiance don’t trigger immediately; only when a creature moves into the spell’s area for the first time on a turn OR starts its turn inside the spell’s area (just like spells like Moonbeam, Spirit Guardians, Cloud of Daggers, etc. — as the Sage Advice Compendium describes on page 19).
It doesn’t matter if a creature willingly moves into its area or not; as long as it MOVES or IS MOVED into the area during a turn, it must pass a Constitution saving throw or else suffer the spell’s negative effects.
Exhaustion comes with the following effects:
Level 1: Disadvantage on ability checks
Level 2: Speed halved
Level 3: Disadvantage on attack rolls and saving throws
Level 4: Hit point maximum halved
Level 5: Speed reduced to 0
Level 6: Death
So, theoretically, a creature who stays in range of Sickening Radiance long enough to fail 6 Constitution saving throws just straight-up dies.
How to Use Sickening Radiance in 5e
Here are a few ways to use Sickening Radiance in DnD 5e:
Slow enemy movement. Spells like Plant Growth, Spike Growth, Grease, Erupting Earth, Insect Plague, etc. are great for slowing all the creatures in the area (although some also require concentration, so you’ll need to buddy up with a second spellcaster to pull these combos off).
The reasoning is simple: most creatures will simply run out of the spell’s area of effect in a turn or two, avoiding all the spell’s negative effects (although the exhaustion/anti-invis effects will remain until the spell ends). Even a creature at the center of the spell’s radius can Dash and be safe in a single round…unless you slow them down, or use one of the next tips…
Restrain foes in the area. A spell like Entangle (area of effect restrained condition) is perfect for this. But even something as simple as having your group’s Barbarian Grapple foes (from the spell’s perimeter, so they don’t suffer the negative effects themselves) can work wonders.
Pair it with Forcecage or Wall of Force. Lovingly referred to as “the microwave” by 5e players, these combinations can effectively kill any creature in the game who’s unable to break free before failing 6 Con saves. Forcecage (7th-level spell, 1-hour duration) is the optimal choice, since it doesn’t require concentration, and the “cage” option (as opposed to the box) can be put up BEFORE you cast Sickening Radiance.
A creature can only get out via magical means, and attempting to teleport requires a successful Charisma saving throw, and ethereal travel doesn’t allow a creature to pass through the cage.
A lower-level option is to use Wall of Force (5th-level, 10-minute duration) to make a hemispherical dome to trap a creature in a space with Sickening Radiance. Creatures within can exit with teleportation spells or the Disintegrate spell, but Dispel Magic and ethereal travel don’t work. The downside is that it requires concentration, so you need at least two spellcasters to make this work.
Even Wall of Stone can work to some degree for this trick, but it also requires concentration and is also 5th-level, and creatures can simply attack panels of the wall (15 AC, 30 hp), making it less effective than the above two options.
Push/pull enemies out of/into it repeatedly. Thunderwave, Thornwhip, Eldritch Blast with the Repelling Blast and/or Grasp of Hadar Eldritch Invocations, or even the Shove action are great combinations with Sickening Radiance. Like the Spike Growth “cheese grater” method, this relies on forcing a creature to make multiple saving throws per round to stack up exhaustion and radiance damage more quickly.
While you’re still limited to one tick per TURN, if multiple allies have these types of abilities, you can easily trigger multiple saves per ROUND. Talk about putting the microwave on full blast…
Be an Evocation Wizard. Sculpt Spells is a 2nd-levle feature that allows you to cause your allies to automatically pass their saving throws against evocation spells (which Sickening Radiance is). That makes it much easier to keep enemies in the spell’s area of effect and generally fight safely while enemies suffer through it.
Deny invisible foes. This is the least impactful part of the spell (seeing as the 1st-level Faerie Fire can achieve the same thing), but it does have multiple opportunities to reveal invisible enemies, taking away their attack advantage/your allies’ attack disadvantage against them.
Lock enemies in a room. If you can somehow catch enemies unaware and bar their exits from a confined space, you can cook them to death with Sickening Radiance. Regular locks + Arcane Lock and only one exit is the prime situation to use this combination, as a poor man’s Forcecage.
Even if you can just bar the door somehow, you’ll have great success with this tactic…although enemies will likely break the door down before instantly dying via exhaustion stacks, and it’s effectively no different than lighting a room on fire and doing the same thing.
What Are the Rules for Sickening Radiance in 5e?
The rules for Sickening Radiance in DnD 5e are as follows:
The effect can trigger multiple times per round, but only once per turn. From the Sage Advice Compendium: “Keep in mind, however, that a creature is subjected to such an area of effect only the first time it enters the area on a turn. You can’t move a creature in and out of it to damage it over and over again on the same turn.” (SAC 19)
Being pushed into the spell’s area prompts an immediate saving throw. From the Sage Advice Compendium: “Entering such an area of effect needn’t be voluntary, unless a spell says otherwise. You can, therefore, hurl a creature into the area with a spell like Thunderwave. We consider that clever play, not an imbalance, so hurl away!” (SAC 19)
Creatures remain dead from exhaustion after Sickening Radiance ends. If you die from 6 levels of exhaustion via Sickening Radiance, it doesn’t matter that those levels of exhaustion go away once the spell ends — once you’re dead, you’re dead (Sage Advice confirmation from Jeremy Crawford).
The Careful Spell metamagmic only works on the first turn of Sickening Radiance. And therefore does nothing, since no creatures are making savings on the turn you cast it; they’re not making saves until it’s their turn.
— Jeremy Crawford (@JeremyECrawford) March 10, 2017
Is Sickening Radiance 5e a Good Spell?
Yes, Sickening Radiance is a good spell in DnD 5e. While Constitution saves are the best average saving throws among 5e’s monsters, its large area, potent and multiple effects, and ability to pair extremely well with other effects that keep enemies within its area of effect make it dominant in certain scenarios.
That being said, Sickening Radiance isn’t all that great in a vacuum. Other spells of equal level do more damage and/or have greater effects. It’s a spell that does a lot of things well, but nothing that great…unless you can pair it with something like Forcecage, at which point it becomes nearly unstoppable.
Sickening Radiance 5e DM Tips
I’ve seen many DMs ask what to do about the “microwave” combo (Forcecage/Wall of Force + Sickening Radiance). It’s really a question of how to exit the area, and there are a couple of options.
Dispel Magic. Works on Forcecage, but you’ll need to upcast it or succeed on a DC 17 ability check using the creature’s spellcasting ability modifier to break free (or just a DC 14 check to end the Sickening Radiance itself). Doesn’t work on Wall of Force.
Break concentration. Minions not trapped in the Forcecage/Wall of Force can try to break the Sickening Radiance caster’s concentration, thus ending the spell early, and dropping all stacks of exhaustion instantly.
Teleport. Teleporting works on Wall of Force no problem, but you’ll need to pass a Charisma save to break free from Forcecage.