Suspicion

In certain stories, a character’s anonymity can be essential to a group’s goals. During such activities, a suspicion meter can be used in places where characters’ presence or visibility is unavoidable but they desire to remain incognito. In certain situations of indiscretion, like using thieves’ tools in a crowded market, a DM might be encouraged to call for NPCs to be suspicious even if the task succeeds.

Suspicion in Play

The suspicion meter threshold for a typical encounter is equal to the number of characters multiplied by 100. For example, if your table consists of four characters, the threshold is set to 400.
When a character fails an ability check that might leave them exposed, whether Dexterity (Stealth) or Charisma (Persuasion), instead a DM can treat the failed check as a Suspicion check. Now, you can determine the level of suspicion surrounding the party as a result of the failure in place of the encounter devolving directly into combat.
To establish the suspicion gained an NPC or group of NPCs on a failure, the character rolls percentile dice and adds the result to the party’s suspicion meter starting at 0. For group checks, each individual failure increases the meter. If the party exceeds the suspicion meter threshold, all the characters in the party become suspicious to the appropriate NPCs and any number of effects may be imposed upon them depending on the adventure (see “Adjusting the Suspicion Meter”). If the party gains a level of suspicion as their presence becomes known, the DM can continue to ask for suspicion checks. Additional failed checks increase the suspicion level by 1.

Suspicion at Work

Suspicion is measured in three levels which can, affect any suspicion-based check or saving throw, are cumulative, and don't reset between encounters:

Suspicion Level

Level	Effect
1	Suspicion check DCs increase by the party’s number
2	NPCs gain advantage on Wisdom ability checks
3	NPCs gain advantage on rolling initiative rolls

Adjusting the Suspicion Meter

If the party has been discovered but completes the encounter, the suspicion level reduces by 1. However, in some cases the adventure might dictate, this meter might reset as the characters move from encounter to encounter or at the DM’s discretion.
If a player rolls a 100 on the percentile dice, the suspicion meter reduces by 100 or suspicion level reduces by 1, if the suspicion meter has already been exceeded. DMs could use their discretion to reduce the suspicion level in other situations. For instance, if a character rolls a natural 20 on an ability check that would otherwise add to the suspicion meter, a DM could reduce the suspicion meter or suspicion level.
A DM can increase the suspense of this mechanic by rolling the percentile dice and tracking the suspicion meter in secret. Thoughtful use of the suspicion meter can prevent the fear of instant failure that causes “choice paralysis” and hinders roleplay. If a PC jumps directly into roleplay, the percentile dice roll can be modified or negated all together.