When Perception contests Stealth, how do you know which side gets advantage or disadvantage?

When we run skill contests, especially Stealth contested by Perception, we sometimes struggle to work out whether to apply advantage to one skill or disadvantage to the other. It matters for two reasons:

  • multiple advantages and disadvantages don’t stack for any single skill check
  • advantage and disadvantage cancel each other out

An example may serve to illustrate:


Example

The dwarven fighter became separated from the rest of the party and was stuck in a long dark tunnel with three human cultists bearing down on her; they were carrying lights but she was still in darkness. She made a Stealth check to hide from them because she wanted to shoot at them with advantage. Here’s how I ruled advantage and disadvantage would stack up on the respective Stealth and Perception checks:

  • The fighter‘s Stealth check had advantage owing to being heavily obscured in the darkness
  • The fighter’s Stealth check had advantage due to her boots of elvenkind
  • The fighter’s Stealth check had disadvantage due to her armour
  • The fighter made a standard Stealth check because the advantage and disadvantage cancelled out; the second advantage did not come into play
  • The cultists‘ Perception check had advantage because they had already been attacked by the fighter, they knew she was hiding in the darkness up ahead of them, and they expected further attacks to come from that direction.
  • The net result was that a standard Stealth check was contested by an advantaged Perception check.

Reviewing the PHB rules on Light and Vision afterwards, I realised I should have made the heavy obscurement into a disadvantage for the cultists. That would have changed the skill contest as follows:

  • The advantage to the fighter‘s Stealth check granted by being heavily obscured would have become a disadvantage to the cultists’ Perception check.
  • The fighter would still have made a standard Stealth check because she would still have had advantage and disadvantage, which would cancel out
  • The cultists‘ Perception check would have had disadvantage because the fighter was heavily obscured from them
  • The cultists would now have made a standard Perception check because their existing advantage would have been cancelled out by the new source of disadvantage
  • The net result would then have been: a standard Stealth check was contested by a standard Perception check.

I’d given the cultists an unwarranted leg-up.


So the question is, for the factors that affect the Stealth vs Perception skill contest, which do you apply to the Stealth check, and which do you apply to the Perception check?

Your reply should address some or all of the following factors, saying which check each applies to, and why:

  • movement of the stealthing or perceiving creature
  • obscurement
  • cover
  • camouflage
  • attention or distraction of perceiving creature
  • ambient light, noise or smell

How do I calculate d20 success probability using the Halfling ‘lucky’ trait with (dis)advantage?

Here is a comprehensive DPR calculator, and here is the mathematics behind it. I’m trying to follow along with the equations.

At the bottom of the second page are formulas for success probability $ L$ of a Halfling (who has luck) in normal circumstances and with advantage and disadvantage: $ $ L = P + \frac{1}{20}P,$ $ $ $ L_{adv} = P_{adv} + \left(\frac{2}{20}(1 – P) – \frac{1}{400}\right)P,$ $ $ $ L_{dis} = P_{dis} + \frac{2}{20}P^2,$ $ where:

  • $ P$ is the probability of succeeding on any single roll,
  • $ P_{adv} = 1 – (1 – P)^2$ is the probability of succeeding with advantage (not failing both rolls), and
  • $ P_{dis} = P^2$ is the probability of succeeding with disadvantage (succeeding both rolls).

The $ P$ s are quite easy to derive, and $ L$ is just passing outright OR [rolling a 1 AND THEN passing]: $ $ P + \left(\frac{1}{20}*P\right).$ $ But I’m struggling with deriving $ L_{adv}$ and $ L_{dis}$ . Please can someone show a derivation?

What’s worse, -2 or disadvantage?

So, I’m building a system that adds an extra level of flavor, with some minor mechanics as an optional side system for a 5e campaign. The basic function is, you collect points, then collect a deficit. Once you get enough points again, that deficit is escalated.

So for example, one effect causes creatures making a perception check (based on smell), gain advantage. The escalated version is they no longer need a roll – they can pick up your trail easily, and are able to track you.

One mechanic I’m not sure about however is the comparison between a hard deficit, vs disadvantage. I.e. -2 to a roll, vs disadvantage on a roll.

So, are these comparable, and if so, which is worse?

Forcing a saving throw to be made with disadvantage

I know there is already a similar question, but it doesn’t really give me an answer. Is there such a thing as a feat or an item that causes enemies to make saving throws like wisdom or general saving throws with disadvantage? I wanted to create a spellcaster (dont know which class yet) who specializes in CC and spells like Phantasmal Killer, but I don’t feel like a high spellcast mod. would really cut the deal to make the CC a little more reliable.

Will it be a significant disadvantage to play a tiny character?

I’m looking to play in my first Starfinders game, and am delighted by the variety of races available. My inclination is to play a Raxilite Biohacker. I’m very familiar with Pathfinder but just starting to learn about Starfinder.

Raxilites are Tiny, but their LFAN counts as a single Medium sized arm (in addition to my two Tiny arms). I see that Tiny doesn’t change To Hit, Damage Dice, AC, Stealth. What it does do is

  • Help with getting into small spaces, and perhaps give better cover options (sounds somewhat helpful),
  • Eliminate my reach (not a biggie for a ranged character) and
  • Require me to buy Tiny weapons–which cost 2x as much as Small/Medium/Large/Huge weapons, as per:

    Weapons are built to be easily held and used by both Small and Medium creatures. Weapons can be built for use by smaller creatures but generally cost twice as much (since they require special miniaturization technology).

In practice, I assume that means over time I’ll choose between:

  1. Using a (Medium-sized) Small Arm, or
  2. Paying 2x for a (Tiny) rifle

It’s fine if my character idea isn’t totally optimized…but I’m a bit nervous that I don’t know just how big a disadvantage this will be over time. (How do Small Arms compare over time with sniper and longarms? How big a hit to Wealth By Level to pay 2x for any longarm or sniper rifle? Are there significant advantages I’m missing to being Tiny in Starfinder, that might make up for the penalties?)

Do you have disadvantage on Con saves against poison while sleeping?

NPCs are going to poison the party while they sleep, do the players have disadvantage on their saves?

Lemme explain. I just started a campaign with a group I was once a player, their lvl 5 characters are on a ship sleeping in the spare crew cabin, but they do not know that its a pirate ship. When they went to sleep it was approximately 3pm and the Pirate Captain found out that they may want to leave before her plan to get some treasure is put through. So she wants more info on the characters and I was planning to have the characters while they are sleeping be exposed to ‘Essence of Ether’ which is dropped down a small hole above deck. Since they are asleep and STR and DEX checks auto fail and you cant really stop yourself from breathing mid sleep, do they have disadvantage on a CON save?

5e Inside Giant Toad, blinded and restrained but also unseen, disadvantage to attack the Toad or not?

When swallowed by a “Giant Toad” you are “Blinded” and “Restrained” giving you disadvantage on attacks.

However you also have “total cover against attacks and other effects outside the toad”.

The Toads eyes are outside the Toad, I certainly don’t see anything inside my own stomach, so doesn’t this mean you are considered Unseen when swallowed?

PHB: Chapter 9: Combat Unseen Attackers and Targets (pg 194-195) “When a creature can’t see you, you have advantage on Attack rolls against it.”

So the Disadvantage and Advantage Cancel out. And an attack against the Toad from within has no advantage or disadvantage.

Question is this then:

Am I unseen while swallowed?

Does the War Caster feat grant ranged spell attacks in melee range without disadvantage?

An opportunity attack is described this way (PHB, p. 195):

You can make an opportunity attack when a hostile creature that you can see moves out of your reach. To make the opportunity attack, you use your reaction to make one melee attack against the provoking creature.

The last benefit of the War Caster feat says (PHB, p. 170):

  • When a hostile creature’s movement provokes an opportunity attack from you, you can use your reaction to cast a spell at the creature, rather than making an opportunity attack. The spell must have a casting time of 1 action and must target only that creature.

Without the Crossbow Expert feat, all ranged attacks (including ranged spell attacks) made when an enemy is adjacent suffer this penalty (PHB, p. 195):

You have disadvantage on a ranged attack roll if you are within 5 feet of a hostile creature that can see you and that isn’t incapacitated.

As an opportunity attack normally grants a melee attack, does it seem reasonable to assume that the target remains at melee range for the spell attack granted by War Caster? If so, does this require ranged spell attack rolls to be made with disadvantage?

The trigger for an OA is a creature moving “out of your reach”. This suggests to me that the creature is out of the 5′ disadvantage zone, but it seems like that would preclude making a melee spell attack.

Do characters with the War Caster feat get the best of both worlds: being allowed to make either a melee spell attack or a non-disadvantaged ranged spell attack?

Can a restrained Sorcerer use the Subtle Spell metamagic to cast attack spells without disadvantage?

Just like it says. We have a Sorcerer who is under the Restrained condition, which says that attacks made by the Sorcerer are made with disadvantage. But the Sorcerer has the Subtle Spell metamagic option and thus would not need to speak or move to cast spells.

Can a restrained Sorcerer use the Subtle Spell metamagic to cast attack spells without disadvantage? Whichever way the answer goes, what’s the in-game rationale?