[RPG] Is actively altering Passive perception a bad thing


I am running a campaign that is tied heavily to lovecraft. I got the idea of using Passive Perception as an actively changed stat, like HP. The new premise of the stat I am proposing is as follows:

  • If passive perception (P.P.) reaches 0, you go (completely) insane and die.
  • A failed death throw lowers P.P. by 1.
  • You can fail as many death throws as you like, so long as you have the P.P. to supply them.
  • A long rest restores P.P. by one (up to a max 10+Wis_Mod+Int_Mod)
  • Items, and events (eg: not sleeping) can lower and raise P.P.
  • P.P. Has the same functions as Vanilla P.P. in addition to these rules.

How this ties into Lovecraftian horror, is that a player with lower P.P. Will perceive the world differently, and start to see more of the 'bigger picture'. For example:

Adventurers come upon a man that is convincing them to save his burning cottage.

  • P.P. 15: The man is a peasant whom likely doesn't have much wealth, judging by his fashion. It would be noble to complete this deed, but likely without reward.
  • P.P. 10: The man seems to be in dire need of this favor, as he is pleading very well, but something seems awry.
  • P.P. 5: Something anomic has set this cottage afire, and this man is no ordinary man, he seems to be heavily influenced by a force.
  • P.P. 1: The cottage contains a fire, and an abhorring entity, you know not its intentions, but fear rushes over you. Why is your party simply standing there? (Note no descriptions about the peasant)

As you can see, the Passive Perception stat changes what people make of the world, and is an integral part of the gameplay. It has an ebb and flow mechanic, where P.P. is a slow stat to move.

This is intended to be new-player friendly, so I think that letting a character fail 10 death throws off one fight, at the cost of sanity is not a bad thing. It provides punishment, but softens the blow of a failed throw. I don't plan on using this to try and draw apart my PCs, but give different observations of the same reality.

So, My question

What trouble does this active altering of passive perception cause for My PCs?

Best Answer

The idea is interesting, but it affects too much other things in terms of the rules. Both Passive checks and Perception skill are core game mechanics, so the game balance will be shaken.

INT-based characters will have abnormal high passive perception checks

At the gaming table, any player should have a chance to shine. Wisdom-based perception proficient Ranger shines, because INT-based low-wisdom Wizards are supposed to have low Perception checks. With the house rule though, any character will have 10 + WIS Mod + INT Mod instead of the normal 10 + WIS mod + Proficiency bonus. That makes character virtually equal in terms of the Perception skill.

Perception proficiency becomes useless

Being proficient in Perception checks should affect passive Perception checks, but it no longer does. This is important for high-level characters, which are proficient in Perception.

Other passive checks seem out of place

There is some inconsistency in changing rules for the Perception skill only. Passive checks aren't tied to the Perception skill, but can be made for any ability check:

A passive check is a special kind of ability check that doesn't involve any die rolls. Such a check can represent the average result for a task done repeatedly, such as searching for secret doors over and over again. or can be used when the DM wants lo secretly determine whether the characters succeed at something without rolling dice

(PHB page 175)

That is consistent with the rest of the rules - for instance, the Observant feat affects both passive Perception (WIS) and Investigation (INT) skill checks.

Combat encounters become non-lethal

Challenging, deadly combat makes your D&D games exciting. However, if your players can just pay for death saving throws, being dropped to 0 hp no more means risk of death. For a horror campaign that becomes crucial, since players won't face actual dangers anymore. Constructing house rules can be fun, but dangerous things should remain dangerous.

It will be hard to prevent meta-gaming

When you describe different things to different players at the same table, it is very hard for players to disengage themselves from that description, especially if they are beginners.


Instead of making a custom rule for passive Perception checks, consider introducing Wisdom ability loss. That gives you the same effects (madness at zero, bad perception results), but doesn't change mechanics so much. Also, the Dungeon Master's Guide has rules for Madness (page 258), that use similar cumulative Sanity score. How NathanS said in the comments below, "Perception would be to see if they notice it at all, but their Sanity score would modify how they interpret it".