Checks, Saves and Combat
Most everything to do with dice-rolling and dice-rolling-adjacent topics, in other words.
making ability checks and saving throws
In general: Please ask the DM before rolling for any checks you may want to make. Generally speaking I'm happy to let you make any check that is reasonably applicable to a situation, but I may want you to make a different check instead ("that's more of an Investigation check than a Perception check, so you can roll Investigation if you want"), and I'd rather know ahead of time what sort of DC you're rolling against than be told "I got a 14 on Survival" and have to figure out the DC after the fact because I didn't realize you were planning on doing whatever you just did.
1s and 20s
Natural 1s and natural 20s on checks and saving throws are not automatic failures or successes (they are still automatic misses and hits, respectively, on attack rolls). If you roll a 1 or 20 on a check or save, you'll still need to account for any modifiers to your roll.
(Technically, this is the standard rule and "natural 1 is a crit fumble on checks" is the house rule, but it's a common enough house rule that I figured I'd clarify anyhow.)
passive checks
I do not generally use "passive Investigation", because honestly that sounds like an oxymoron to me. I do use passive Perception, and may occasionally use passive Insight. You may, however, be able to take 10 or 20 (see below) on an Investigation check if it makes sense in a given situation. The number should work out the same, but it will still involve a deliberate decision on the player's part and active searching around.
group checks and repeated attempts at a check
Generally speaking, unless I say otherwise (usually in a situation where it's obvious that multiple individual checks are needed), a given skill or ability check can only be made once, rather than each party member attempting in turn until someone succeeds. Players have three options:
- A single character can make the check, as normal.
- A single character can make the check with the assistance of one or more characters. Depending on the skill and situation in question, I may require that the assisting characters be proficient in said skill, or may even ask those characters to make their own roll to see whether their attempt to help is successful (for particularly complex or difficult tasks). I will always ask for a description of what the assisting characters are doing and why they think it will help their ally, and may not allow the help attempt if the answer doesn't make sense. If at least one character is successfully able to assist, the character making the check proper can roll with advantage.
- If multiple characters want to make separate checks to accomplish the same task, a group check will be made instead. All characters attempting the action make the check. If at least half of the group (rounded up) succeeds, the check succeeds; otherwise, the check fails.
As an example, Perception checks are generally made individually rather than aided/as a group, as each individual may notice different things. Attempting to help the rogue pick a lock would likely require that the assisting character also be proficient in thieves' tools or a similar skill, as someone with no lockpicking knowledge wouldn't have anything useful to contribute. Investigation checks, on the other hand, could potentially be made with aid or as a group, as the party puts their heads together to share ideas and understand whatever clues they might have found.
An exception can be requested for situations that require skill/have a chance of failure, but which the party does not believe are especially stressful or time-sensitive:
- If the party is not willing to risk waiting around, a single roll (or single aided roll with advantage, or single group check) is used, as normal.
- If the party is willing to try waiting for ten minutes, the character(s) attempting the check may "take 10"—essentially, assume that you roll a 10 on the d20 and add your relevant modifier. This result is achieved at the end of the ten minutes, so if the action is interrupted before that time, no take 10 "roll" is made. Taking 10 is not an automatic success; for example, if taking 10 would result in the character's roll being 14, and the DC for the task is 15, then ten minutes of effort is not enough to accomplish that task.
- If the party is willing to try waiting for one hour, the character(s) attempting the check may "take 20"—essentially, assume that you roll a natural 20 on the d20 and add your relevant modifier. This result is achieved at the end of the hour, so if the action is interrupted before that time, no take 20 "roll" is made. Taking 20 is not an automatic success; for example, if taking 20 would result in the character's roll being 24, and the DC for the task is 25, then one hour of effort is not enough to accomplish that task.
Players must ask to take 10 or take 20, and ideally the party must agree to wait the amount of time required to do so. Characters taking 20 on a task may or may not be allowed to complete a short rest at the same time, depending on how strenuous the task is; other characters not attempting the task can usually take a short rest while they wait.
Obviously, if an action is entirely trivial and non-stressful, no roll should be required in the first place.
skills with different abilities
This is a variant rule from the PHB. I might sometimes allow you to make a skill check with an ability it isn't normally attached to, assuming it's applicable to the situation. The classic example would be a beefy barbarian wanting to intimidate a puny guard. Big McLargeHuge over here doesn't have the greatest Charisma, so ordinarily his Charisma (Intimidate) check wouldn't be likely to go very well, but if Big's player tells me he wants to intimidate the guard by flexing his muscles or by snapping a table in half—feats that prove his incredible Strength, in other words—I might let him make a Strength (Intimidate) check instead, using his Strength modifier in place of his Charisma modifier but maintaining whatever other bonuses to Intimidate he might have (proficiency, etc.). This doesn't come up very often, but if you can convince me that an alternative ability score makes sense, I may let you try it.
seeing in the dark/darkvision
This is also actually the original rule rather than a house rule or variant rule, but since it comes up: Having darkvision means that you treat darkness as dim light, and dim light means that you still have disadvantage on sight-related checks. (Not having darkvision in darkness means that you automatically fail the check outright.) If you don't want to have disadvantage when looking at things, you'll still want a light source of some kind.
It's easy to forget this, and I don't always remember myself, but I want to try to keep this in mind.
combat
Remember that any rules used apply to both PCs and DM-controlled characters!
flanking
I currently use a homebrew variation on the optional "Flanking" rule from the DMG. When two allied creatures are in appropriate flanking position around an enemy—on opposite sides of it while in melee range, more or less—the creature making the attack gets +2 to its attack roll. Flanking does not grant advantage to the attacker. This is mostly to avoid trivializing advantage, as otherwise flanking does silly things like making a barbarian's Reckless Attack feature all but pointless.
I am amenable to not playing with flanking at all, if the players feel strongly about it. Flanking is also generally not used in games that are played using theater of the mind, as tracking position with TotM is enough of a bear as it is.
rolling critical hit damage
I offer my groups the following option: when you roll a natural 20 on an attack roll, instead of rolling double the dice, roll the dice once and add that to the maximum damage (and any modifiers) from whatever a single damage roll would normally be. For example, if you score a critical hit with a rapier and have +3 to damage with that rapier, you would do 8 (max rapier damage) + 1d8 (critical hit) + 3 damage to your target. If you score a critical hit with the spell guiding bolt cast at 1st level, you would do 24 (max guiding bolt damage) + 4d6 (critical hit) damage to your target.
As said above, yes, this does apply to enemies, and yes, it will suck if your character suffers a critical hit. Hence why this is an option: if the group is willing to take the risk of eating a 24+4d6 guiding bolt so that they have the chance to pull off similar damage and avoid the bad feels of rolling a bunch of 1s, they can do so.
drinking potions during combat
Drinking a potion yourself during combat is a bonus action (so long as the potion is reasonably accessible, e.g., not buried in your bag of holding or being held by someone across the room). Feeding a potion to another character is still a standard action.