Radiation (5e Variant Rule)

Radiation

Radiation is a common fixture of post-apocalyptic campaigns, but it's hardly limited to the genre. An enterprising referee can surprise unsuspecting players by throwing radioactive places and objects into any campaign. Like any other rule it can be tons of fun in the right hands.

Mechanics of Radiation

Radiation can come in the form of solar flares, cosmic rays, nuclear accidents, radioactive materials, and nuclear weapons. In a fantasy campaign, you should also consider that the experiments of wizards might leave radioactive byproducts. Just something to keep in mind next time the player characters feel like snooping around a wizard's laboratory.

Radiation works by ionizing flesh. It's like a poison, and for game purposes it should be treated as such. A creature who enters a radioactive area must make a Constitution saving throw with a DC listed on the following chart. On a failed saving throw, the creature takes poison damage based on the radiation's intensity and its hit point maximum is reduced by an amount equal to the damage taken. This reduction lasts as long as long as the character remains ionized. A creature who fails the initial saving throw is allowed to make a new saving throw after an amount of time passes equal to the listing under the "Saving Throw" Column. If the creature fails this new saving throw, the creature continues to take damage and lose maximum hit points.

Other Effects: Higher intensities of radiation can cause different effects besides simple poison damage.

Poisoned: The creature suffers from the poisoned condition as long as it remains ionized.

Weakened: The creature's movement speed is halved. Additionally, the creature only deals half damage with a weapon attack or an unarmed strike. These effects last as long as the creature remains ionized.

Blinded: The creature suffers from the blinded condition as long as it remains ionized.

Drained: Roll a six-sided die. On a roll of 1-2, the creature permanently loses 2 points of Strength. On a roll of 3-4, the creature permanently loses 2 points of Dexterity. On a roll of 5-6, the creature permanently loses 2 points of Constitution.

Table: Radiation Gauge Chart

Intensity	Save DC	Poison Damage	Other Effects	Saving Throw
Very Low	10	1d6		1/hour
Low	13	2d6		1/hour
Medium	15	4d6	Poisoned	1/day
Heavy	18	6d6	Poisoned, Weakened	1/day
Very Heavy	20	8d6	Blinded, Poisoned, Weakened	1/week (7 days)
Deadly	25	10d6	Blinded, Drained, Poisoned, Weakened	1/month (30 days)

Curing Radiation

The effects of radiation can be cured early with the use of magic. Radiation poisoning caused by radiation no worse than Medium in intensity can be cured by any spell or other magical effect which can neutralize poison or end the poisoned condition, such as lesser restoration. Radiation poisoning caused by radiation of Heavy or worse intensity is much more difficult to cure; Only a spell cast with a spell slot of 5th level of higher, such as greater restoration will successfully cure the effects.

Mutations (Optional)

Optionally, if a creature succeeds on a saving throw against radiation by matching the exact DC of the radiation, it might become mutated. For example, if a creature makes a saving throw against Heavy Radiation and rolls a modified 18 exactly, no higher and no lower, it might become mutated. The creature must make another Constitution saving throw against the original DC. On a failed save, instead of suffering from the radiation's effects, the creature becomes mutated. Whenever a creature is mutated, roll a six-sided die: On a 1-3, roll on the negative mutation chart to determine what happens. On a 4-6, roll on the positive mutation chart.

(Yes, I realize this is a variant rule for an already variant rule... sorry.)

A note on psionic powers: In all cases, Charisma is the mutant's spellcasting ability modifier.

Table: Negative Mutation Chart

D20	Result	Effect
1	Ability Score Decrease	The mutant’s Strength score decreases by 2.
2	Ability Score Decrease	The mutant’s Dexterity score decreases by 2.
3	Ability Score Decrease	The mutant’s Constitution score decreases by 2.
4	Ability Score Decrease	The mutant’s Intelligence score decreases by 2.
5	Ability Score Decrease	The mutant’s Wisdom score decreases by 2.
6	Ability Score Decrease	The mutant’s Charisma score decreases by 2.
7	Severely Deformed	The mutant has disadvantage on all Charisma checks except to intimidate.
8	Crippled	The mutant’s speed is reduced by 10 feet, to a minimum of 15 feet.
9	Damage Vulnerability	The mutant becomes vulnerable to a random type of damage. Roll a d10 to determine which: 1 is acid, 2 is cold, 3 is fire, 4 is force, 5 is lightning, 6 is necrotic, 7 is poison, 8 is psychic, 9 is radiant, and 10 is thunder.
10	Sunlight Sensitivity	While in sunlight, the mutant has disadvantage on attack rolls, as well as on Wisdom (Perception) checks that rely on sight.
11	Blinded	The mutant becomes permanently blinded.
12	Defened	The mutant becomes permanently deafened.
13	Berserker	Whenever a hostile creature damages the mutant, it must succeed on a DC 15 Wisdom saving throw or go berserk.
14	Easily Confused	Whenever the mutant rolls for initiative, it must succeed on a DC 15 Wisdom saving throw or be suffer from the effects of the confusion spell for 1 minute.
15	Mentally Disordered	The mutant suffers from disadvantage on all Intelligence checks.
16	Hungry	The mutant's food requirements are tripled.
17	Thirsty	The mutant's water requirements are tripled.
18	Decreased Coordination	Whenever the mutant takes the dash action, it must succeed on a DC 15 Dexterity saving throw or fall prone.
19	Susceptibility Towards Magic	The mutant suffers from disadvantage on saving throws against spells and other magical effects.
20	Nuked	The mutant becomes immune to radiation. However, at the start of each of its turns, each creature within 10 feet of the mutant is exposed to Medium intensity radiation.

Table: Positive Mutation Chart

D20	Result	Effect
1	Ability Score Increase	The mutant’s Strength score increases by 2, to a maximum of 22.
2	Ability Score Increase	The mutant’s Dexterity score increases by 2, to a maximum of 22.
3	Ability Score Increase	The mutant’s Constitution score increases by 2, to a maximum of 22.
4	Ability Score Increase	The mutant’s Intelligence score increases by 2, to a maximum of 22.
5	Ability Score Increase	The mutant’s Wisdom score increases by 2, to a maximum of 22.
6	Ability Score Increase	The mutant’s Charisma score increases by 2, to a maximum of 22.
7	Natural Armor	The mutant's AC while not wearing armor is equal to 13 + its Dexterity modifier.
8	Natural Weaponry	The mutant’s unarmed strikes now deal 1d6 points of bludgeoning, piercing, or slashing damage.
9	Minor Psionics	The mutant can innately cast a sorcerer, warlock, or wizard cantrip of the referee's choice at will, requiring no components.
10	Major Psionice	The mutant can innately cast dominate person three times per day, requiring no components.
11	Major Psionice	The mutant can innately cast telekinesis three times per day, requiring no components.
12	Major Psionice	The mutant can innately cast modify memory three times per day, requiring no components.
13	Major Psionice	The mutant can innately cast dimension door three times per day, requiring no components.
14	Telepathy	The mutant can innately cast detect thoughts at will, requiring no components, and it also gains telepathy to a range of 100 feet.
15	Aquatic Adaption	The mutant can breathe underwater, and it gains a swim speed equal to its walking speed.
16	Jumper	The mutant's jump distance is tripled.
17	Damage Resistance	The mutant becomes resistant to a random type of damage. Roll a d10 to determine which: 1 is acid, 2 is cold, 3 is fire, 4 is force, 5 is lightning, 6 is necrotic, 7 is poison, 8 is psychic, 9 is radiant, and 10 is thunder.
18	Invisibility	The mutant gains the ability to turn invisible as an action. Anything it is wearing or carrying becomes invisible with it. The mutant remains invisible until it attacks or casts a spell, or until it uses a bonus action to become visible again.
19	Magic Resistance	The mutant has advantage on saving throws against spells and other magical effects.
20	Quickened	The mutant's speed increases by 15 feet.

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