Illusion Storm (5e Hazard)
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An illusion storm is a mysterious surge of illusory magic that becomes self-sustaining for 12 to 48 hours, spreading terror and wonder until it clears. Illusion storms only occasionally pose a direct threat, but they are known for making things difficult and confusing. The storm takes the form of a great cloud, between 200 and 500 feet wide, and it can affect areas up to 1 mile away. It appears as a chaotic, amorphous amalgamation of all things. Mountains, men, dragons, beasts, cottages and castles, anything and everything that can be found in the material plane may be seen and heard by audiences of an illusion storm. Within it, these illusions fly, stretch, twist, and bend in impossible ways, swirling about like a volatile liquid. Some storms move in a specific direction over time, some remain still, and some attempt to spread out in all directions before tearing and fading out.
Any creature that looks directly at the storm must succeed on a DC 10 Wisdom saving throw. On a failed save, the creature is stunned for 1 minute or until their line of sight with the storm is broken. On a successful save, the creature is immune to this effect for 1 hour.
All illusions within the cloud produce sound if appropriate. This leads to a constant, droning cacophony which seems to absorb real sounds. All Wisdom (Perception) made to hear within the affected area have disadvantage.
Within the affected area, illusion spells become less taxing to cast. Illusion spells of 1st level can be cast at their lowest level without expending a spell slot. Illusion spells of 2nd level or higher can be cast at their lowest level by expending a spell slot that is one level lower. To cast an illusion spell at a higher level, creatures must expend a higher level spell slot as normal. For example, a wizard could cast invisibility as a 2nd level spell by expending a 1st level spell slot, but must still expend a 3rd level slot to target an additional creature with the spell.
Conversely, divination spells become unreliable. When a creature within the affected area casts or becomes the target of a divination spell which reveals information, the spell will instead reveal false or random information. Spells which allow speaking new languages often cause mistranslations. Detection spells may fail to work, produce false positives, or trigger in response to an illusion. Location finders produce random, shifting directions. Sensory divinations produce illusory scenes, which may be nonsensical or highly believable. Spells meant to contact extraplanar entities may instead choose a random target or simply produce illusory responses. Generally, any time a creature would receive information from a magical source, that information may be changed or lost at the DM's discretion.
An additional effect is produced every minute within the affected area. Roll a d20 on the chart below to determine the effect. If an effect requires a saving throw, the DC for the save is 15. Generally, one effect is produced for each 200 foot cube of area. When a new effect is produced, the previous one ends.
|1||A minor illusion appears.|
|2||1d12 minor illusions appear.|
|3||A multicolored spark descends from the cloud and bursts 100 feet overhead. It casts color spray pointed downward as a 3rd level spell with an unlimited range.|
|4||All creatures are affected by the disguise self spell.|
|5||All written text is subject to the effect of the illusory script spell, becoming unintelligible.|
|6||A silent image appears.|
|7||1d8 silent images appear.|
|8||All creatures are affected by the blur spell.|
|9||1d6 random creatures are affected by the invisibility spell.|
|10||1d4 random creatures are affected by the mirror image spell.|
|11||A phantasmal force appears, visible to all creatures. There is no saving throw to avoid perceiving it.|
|12||Blades of shadow rain from the sky. Creatures must succeed on a Dexterity saving throw at the beginning of each of their turns or take 1d4 psychic damage.|
|13||A 100-foot-radius sphere of silence appears.|
|14||A dark, writhing spark descends from the cloud and bursts 50 feet overhead. It casts fear pointed downward with an unlimited range.|
|15||A hypnotic pattern appears.|
|16||A major image appears.|
|17||1d4 major images appear.|
|18||A random creature is affected by the greater invisibility spell.|
|19||A patch of hallucinatory terrain appears.|
|20||A phantasmal killer appears to a random creature.|