Effects on chance

[Caels]

Please forgive me if this is answered already, I did search but maybe I'm not searching for the right terms.

I'm putting together a custom game based on the 5E rules.

Is there a way to trigger an effect based on a die roll?

For clarity, I've created a custom effect that will apply to lots of creatures throughout the campaign called Corrupted. A creature affected by corruption is immune to sleep, charm, fear and other such affects. But I'd also like to add in a very small chance of the corruption spreading through melee attacks.

I was thinking perhaps something like CHECK: 1d100, or SAVE 1d100, but I don't know how I would tie that to a resulting roll or even compare it to whatever chance I'm after.

[Zacchaeus]

Short answer is no you can’t tie an effect (or anything else) based off a dice roll.

You could possibly use the critical and fumbles table to do something like what you need but of course that only fires on critical sand fumbles rather than on a hit. Having to make a saving throw vs the corruption only on a critical hit seems to me to be a reasonable way of doing things however rather than against all hits. Even with.a 1% change to get corrupted the entire party will be infected after a couple of sessions.

[Caels]

Aye, the corruption isn't meant for the players, but rather the ever shrinking population of ruined civilization. There would be battles in which the players must protect villages/inhabitants and they would eventually be able to convince NPCs to join them in their own strongholds... If they can get them there safely.

A bit strange for a 5E game, sure, but I'm trying to build story and suspense just as much as strange rules... You'd probably hate to see what I'm doing to the magic systems.

Thank you for your feedback :) Also, thank you for your videos on effects. They helped me develop this (un?)healthy appetite for tweaking the system.