In the comments for another question, I was asked to pose a question on how to achieve a passive Perception of 28, while having a Perception modifier significantly lower than 18, which is impossible to achieve.
So, here's the question:
How do you achieve a passive Perception of 28, with a bonus to active Perception of less than 10?
Using a combination of feats and magic items, it is possible to achieve a passive perception that is incredibly high. I will use the build my player of a dwarven cleric made as my example.
First off, he had a wisdom score of 20, giving a +5 to both active and passive perception.
Secondly, he was proficient in perception, and was level 5, giving a further +3 to both active and passive perception, for a total of +8.
Thirdly, he had the Observant feat, which grants a +5 bonus to passive perception and investigation rolls, totalling a +13 to passive perception, which would be a passive perception of 23.
Fourthly, he had a magic item, namely the Sentinel Shield, which gives you advantage on initiative rolls and perception checks. Having advantage on passive checks confers a +5 to the passive score, bringing it up to a total of 28.
The only way his active perception could ever match his passive is if he rolled a natural 20, or had disadvantage on the roll, cancelling out the advantage, and requiring he roll a 15 or higher.
The observant feat gives +5 to passive perception checks, and advantage gives another +5. This means your passive perception bonus is +10, for a total of 20, with a perception bonus of +0.
I believe this is the maximum difference attainable between passive and active perception.
If you gain +8 through other means (eg proficiency in perception with +3 proficiency bonus and +5 from wisdom) you will have 28 passive perception and +8 perception bonus.
When utilizing Customized Ability Scores (point buy, standard array, etc) the earliest level you could get a 28 to your passive perception is 6:
Customized rules make it so that you can only put 15 in a starting stat before racial abilities, so the most you can have in Wisdom is 16 at level 1 (no races give a +2).
Human variant, Fighter level 1 - This allows for a starting stat of 16 in Wisdom, as well as picking up the Observant feat right off the bat to increase passive perception by +5. You obviously take Perception as your skill for the proficiency bonus.
Level 1 Current passive perception: 10 + Prof + Wis + Observant = 10 + 2 + 3 + 5 = 20
Now you need to wait until level 6 to get both ASI's to move your Wisdom up to the required 20 to get the +5 from Wisdom.
Level 6 Current passive perception: 10 + Prof + Wis + Observant = 10 + 3 + 5 + 5 = 23
Then, if your DM permits the wording on Sentinel Shield to grant you +5 passive perception bonus, you add that as well. This item is of relatively low level and shouldn't be too hard to obtain.
If using rolls for stats, you can reach this goal slightly faster.
A roll of 18 will get you the +4 right away, and taking human variant will get you Observant as well. Take whatever class you like, and the first ASI level gets your Wisdom up to 20 to maximize the passive perception your character can have without magical assistance. Add in the Sentinel Shield and proficiency bonus again, and your character is set at 28 before level 5.
Using point buy put 15 into Wisdom, take Human Variant to get Wis +1, starting is Wisdom 16 (+3), take proficiency in Perception and then a class that gives Expertise, such as 1 level of Rogue or 3 levels of Bard (giving starting proficiency of +4). Your active perception modifier is +7.
To get a higher passive perception, for your Human Variant feat take Observant, which gives +5 passive.
Next get advantage, either by having someone cast Enhance Ability - Owl's Wisdom on you or get your hands on a magic item such as Sentinel Shield, Eyes of the Eagle, Robe of Eyes, or Candle of Invocation. The highest you can roll as an active check is still 27, but you get two chances. Having advantage grants another +5 passive.
It is the combination of the Observant feat and Advantage that give the +10 boost to passive perception.
At first level a Rogue can have a passive perception of 27.
To get to 28 passive you need a +8 active modifier, which at first level will require a Wisdom of 18 either through a magic item boost such as a Tome of Understanding, or an Ioun Stone of Insight (or, if rolling ability scores a rolled 18 would give this), or wait until you can get an ability increase at level 4.
If you increase Wisdom to 18, so your active is +8, then you can get a passive of 28.
Note that a Human Variant Bard can achieve passive perception of 28 at level 4 without any magic items, as they get Expertise at level 3, and can also cast Enhance Ability on themselves.
At 5th level, your proficiency (doubled by Expertise) increases, adding another +2 to both.
I know this thread is quite old but I just wanted to post that this number can be upped by a good bit not including items sense no items upgrade passive perception as most people in this thread keep over looking the specific text of ability “check” passive perception is not an ability check of any kind Nor does advantage = a +5. Percentage yes I suppose it is a 5 but that’s not how the item functions. However i will also leave a number for if we did count “checks” and advantage.
Total result 10 base +5 wisdom +5 observant +6 proficiency +6 prodigy
Total= 32
If we count “checks” and advantages we repeat the previous steps but add some.
Total result 10 base +5 wisdom +5 observant +6 proficiency +6 prodigy +5 from hearth of moonlight and shadow +5 from sentinel shield +1 from luck stone
For a grand total of: 43
For this, I actually figured this out.
All total, the formula will look like this:
10 (base)
+ 12 (proficiency bonus)
+ 6 (Wisdom modifier)
+ 5 (Observant)
+ 5 (advantage)
+ 1 (Luckstone)
= 39
Okay so I'm building a character around max Passive perception and here is what I've come up with.
DC 30 checks are considered nearly impossible,42 must be supernatural. Nothing can hide from you.
