Please help me to balance disease, that turns you into butterflies

[MercuryAlloy]

So I'm new to 4e, and I was unable to find the rules for creation of diseases. I want to create a low-level disease that kobolds can throw in you among other dirty tricks with some Lovecraft vibes.

I use a few cosmetic homerules here :

1. Endurance check is made at the end of disease cycle, rather then every long rest.
2. You don't know what the disease is, unless your are able to identify it, which may be harder or easier on a different stage.
3. Once you identify disease you can make an additional check about special treatment, that can help you to cure disease if special conditions are met.

I planned it as a slow disease, that gradually grows from sweet to nightmarish and gives players time to discover what the hell is going on. I still unsure about numbers and ask you to help with them.

Here what I have so far:
https://sun9-39.userapi.com/impg/qefGBDsDuNxKV80Wd4Nqx1g4TkUkKB2wEwJmTw/jZvyfFD-mtI.jpg?size=524x607&quality=96&sign=cb1f90e0c4f91e556ff9aa5ffa6e22f8&type=album

[Beoric]

I think your houserules are fine. I have used shorter check intervals without experiencing any problems, as long as the intervals are long enough for the players to have a reasonable chance to do something about the disease.

I wouldn't use a random number of checks per day because it does not tell you the interval between checks. I would make it a fixed 4 hour interval, or maybe every 2d4-1 hours if you really want randomness.

Interesting choice to start the disease with a buff instead of a debuff. That will lure your players into not thinking this is a disease; whether that is fair or not depends on your playstyle. You seem to be implying that failing to identify the disease makes it harder to cure (although that is not refected in the entry). Assuming that to be true, and given that stage 1 is a red herring, and the fact the players don't get a full day between stages of the disease, I think your DCs to identify are too high to identify it. I mean, the DC at stage 1 is Hard+4, that's a bit over the top.

Your maintain/improve DCs are also too high for a level 4 disease. Maintain DC should be Easy (DC 10), improve DC should be Moderate (D 14).

I think the general rule for creating diseases is to make stage 1 a minor debuff; stage 2 a moderate to serious debuff; and stage 3 or 4 anything up to and including fatality.

[Anxe]

A disease that kills PCs probably isn't level 4.

[Beoric]

A disease that kills PCs probably isn't level 4.

Rot Grub Infestation is level 4, and it kills you at stage 3. And it's in a core rulebook.

[MercuryAlloy]

I think your houserules are fine. I have used shorter check intervals without experiencing any problems, as long as the intervals are long enough for the players to have a reasonable chance to do something about the disease.

I wouldn't use a random number of checks per day because it does not tell you the interval between checks. I would make it a fixed 4 hour interval, or maybe every 2d4-1 hours if you really want randomness.

Interesting choice to start the disease with a buff instead of a debuff. That will lure your players into not thinking this is a disease; whether that is fair or not depends on your playstyle. You seem to be implying that failing to identify the disease makes it harder to cure (although that is not refected in the entry). Assuming that to be true, and given that stage 1 is a red herring, and the fact the players don't get a full day between stages of the disease, I think your DCs to identify are too high to identify it. I mean, the DC at stage 1 is Hard+4, that's a bit over the top.

Your maintain/improve DCs are also too high for a level 4 disease. Maintain DC should be Easy (DC 10), improve DC should be Moderate (D 14).

I think the general rule for creating diseases is to make stage 1 a minor debuff; stage 2 a moderate to serious debuff; and stage 3 or 4 anything up to and including fatality.

Thank you, but they actually have several days between endurance checks (disease cycle is an interval between such checks) to get aware of the condition on each stage, and failure at identification does not prevent you from performing Curing disease ritual. Identification is merely for knowing what the disease is, how it spreads and how it works.

With Endurance DC I oriented of the Filth Fever, that has DC 16 for maintain and 21 for improving, but you are probably right, they are a bit too high.

[tiornys]

With Endurance DC I oriented of the Filth Fever, that has DC 16 for maintain and 21 for improving, but you are probably right, they are a bit too high.
Disease DCs are based on skill difficulty levels. Skill difficulty levels as presented in the original core books were later reduced by errata when WotC determined they had been set too high. If you look at post-errata versions of Filth Fever (e.g from Monster Vault) you'll see that they have a maintain check of based on the Easy DC for the level of the disease and an improve check based on the moderate DC. For Dire Rat Filth Fever (level 1) that's maintain of 8 and improve of 12. Thus a level 4 disease should have maintain DC 10 and improve DC 14 as stated by Beoric.