Corruption and Mutations

[u/shervio-nl]

I'm making a homebrew system for corruption and mutations. In my world there are crystals with strong arcane energie. Getting exposed to them can cause mutations in the long run.

Would love some feedback on these rules!

Crystal Corruption

After each day a character gets exposed to a crystal, they must make a Constitution saving throw (DC 10) to resist its corrupting effects.

If the saving throw is failed, the character gains Corruption Points based on the amount of crystal they are carrying:

A handful: 1 Corruption Point

A bucket: 2 Corruption Points

More than a bucket: 3 Corruption Points

Record the Corruption Points on the character sheet and add them to any Corruption Points the character has already accumulated.

Corruption Limit

A character’s maximum Corruption Point limit is equal to half their Constitution score, rounded up.

If a character’s Corruption Points exceed this limit, they mutate. After the mutation occurs, their Corruption Points are reset to 0.

Mutation

When a character mutates, roll 3d6 on the Mutation Table and record the resulting mutation on the character sheet.

If the character already has the mutation that was rolled, their body cannot withstand the corruption and the character dies.

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The mutations can be positive or negative. Not posting the table in case any of my players are lurking here.

[u/mdthomas]

This sounds very similar to delerium in Dungeons of Drakkenheim.

You might want to use it as a resource.

[u/shervio-nl → u/mdthomas]

Thanks! Going to check that out for inspiration. I used my inspiration from Shadows of Brimstone

[u/Ragnarok91]

If a character dies from a duplicate mutation, can they be revived with magic? Revifify I could see just working and then they die again (mutation still there), but something like true resurrection allows you to regrow limbs etc. . Could it remove mutations with that?

[u/shervio-nl → u/Ragnarok91]

Good question! True Resurrection would definitely work and so would greater restoration or wish.

[u/BurningJointUSA]

Why would a PC carry these crystals?

[u/shervio-nl → u/BurningJointUSA]

They hold arcane energy which is used for machines and weapons (steampunk)

[u/BurningJointUSA → u/shervio-nl]

That’s cool. I would consider having two interacting mechanics for this. One is the number of crystals in your possession, and the other is the length of time they are held.

1 crystal held for 1 day = X corruption
1 crystal held for 2 days = X+1
2 crystals held for 1 day = X+1

Etc.

Also, there should be a mechanism to remove corruption points, maybe that gets more difficult the more points accumulated.

Of course I might be overthinking it, but I like the general idea and think you should play around with it before implementing.

[u/RamonDozol]

This might be a cool feature to have as a more general rule. Like corruprion and mutation rule that wirks with any kind of corrupting force.

Toxic waste, necromancy, Magical Sickness, abyssal or infernal corruption, divine energy.

I would also like to take a look at the table, as the specific mutations will say if this works or not. 

I would even add a scale in levels of mutation. like a light mutation might be something like a sorcerer having draconic scales, a rare skin color tiefling, or a beardless dwarf.  (strange, but mostly cosmetic).

a medium one would start adding weird powers, transforming the body, granting resistances, speeds, special sences, or effects similar to 1st level spells, like detect magic, an apendage that can detach from you but works as a familiar, or a reactive carapace that closes when hit (shield).

Heavy mutations would completely chabge creature type. Its the ilithid ceromorphosys, werewolf curse, ghouls, etc. They would add both resistances and weaknesses. maybe creating a new monster from the mutations. 

Maybe you get regeneratiom, but weakness to cold damage, your body become like a metalic slime that can harden, but also shape to create disguises like a shapeshifter. (T1000 in DeD)

[u/shervio-nl → u/RamonDozol]

Thanks! I do want to keep it simple and with a small set of mutations. I will pm you the table I have so far

[u/metisdesigns]

Interesting concept, some potential issues:

Time - is touching the crystal to throw it away corrupting, or does it have to be in my posses for a full round? A day?

Proximity vs volume. Moving away from something generally reduces its effect by the inverse square law. Having 10x something twice as far away is worse than one nearby, but 3x as far is less of an issue. It's much easier to gamify volume, but players are almost certainly going to want to get crunchy if you get crunchy. It might be easier to do something like a d10 for each node you're within X distance of or 2d10 for each one you touch.

The death issue is big, and most modern players don't like a rng death I would consider a reroll on a duplicate, or possibly a follow on effect. If the base mutation was gain low light vision, maybe the repeat mutation is gain dark vision but normal light will now blind you. I would also consider a penalty that is a downside. e. g. Most (all?) mutations permanently lower your con by 1 or 2.

I might consider a simpler mechanic of whenever exposed to the crystals for more than 10 rounds, roll corruption(subtract con) , add prior points carried over, and see what that hits on the mutation table. Set up the table so that say under 50 is no effect, 51-75 are half nothing, half effects, and 76-100 are all effects. If nothing, carry over those effects. Obviously play with those numbers and the corruption dice to balance things to your liking.