So this thread, and more specifically
@Hussar 's story about the 3 DM's he played under, inspired me to go back and re-read the DMG section for 5e on Ability checks... and I have to say I was surprised at just how much it did to set out the expected practices of 5e... which contrary to many people's assumptions don't appear to be... do whatever you want (though like any game the DM is free to ignore advice, examples, practices, etc.). I decided to pull excerpts (with commentary) from the DMG below to highlight what I am talking about...
Using Ability Scores...
When to roll
1. When a player wants to do something it's often appropriate to let the attempt succeed without a roll
2. Only call for a roll if there is a meaningful consequence for failure
3. When deciding whether to use a roll ask the following questions
a. Is a task so easy and free of conflict and stress that there should be no chance of failure
b. Is a task so inaapropriate or impossible that it can't work
4. If the answer to both of these questions is no then some type of roll is appropriate
So above we have the process by which a DM should decide to say yes to an action... say no to an action or roll the dice.
Ability Check: A test to see whether a character succeeds at a task that he or she has decided to attempt
The DMG defines what a check represents... specifically the chance to succeed or fail at a single task. Which in turn implies that any action being rolled for should be framed as a single discrete task that has success state and a failure state.
Multiple Ability Checks
- If the only real cost is time yes (a character spending ten times the normal amount of time auto-succeeds at the task)
- If not the circumstances or approach must be changed to attempt again (with a harder DC at the DM's discretion)
Contests
-Use a contest if a character attempts something that either directly foils or is directly opposed by another creature's efforts
- Instead of a DC ability checks are compared to each other
- DM picks the ability that each creature must use
Above we are given the practices for using multiple ability checks and contests as opposed to a regular ability check. Of particular interest is the fact that if players can come up with a new approach or change their circumstances they can roll again. Personally I don't think many DM's enact this specific practice
Difficulty Class
- Think of how difficult a task is and then pick the associated DC from the typical DC's table
- Most people can accomplish a task of DC 5 (Very Easy) with little chance of failure, if a roll is deemed necessary a task usually will not fall into this category. Unless there are unusual circumstances this should be an auto-success
-If not ask yourself if a task's difficulty is easy moderate or hard...If the only DC's you ever use are 10/15/20 your game will be fine
-A DC 10 task is accomplished 50% of the time w/attribute 10 and +0 prof bonus
-You can use a higher DC than 20 but caution and level consideration is advised
So the first thing here is it really brings home how easy it is to determine success rates for an ability check in D&D 5e due to nearly every +1 easily translating into 5% and using DC's that increase in 5 point intervals. But more importantly there are practices laid out above for determining the DC and while one can go beyond them in both the range of the DC and rolling for the DC 5 the game takes time to caution against it except in special circumstances.
Applying Adv/Disadv
-Advantage when: Circumstances provide an edge, An aspect of the environment contribues to success, player shows creativityor cunning in attempting or describing a task, previous actions improve success.
-Disadv when: Circumstances hinder success, an aspect of the environment hinders success, some aspect of a plan or descriotion makes success less likely.
Resolution & Consequences
-As DM you determine the consequences of attack rolls, ability checks and saving throws
-In most cases doing so is straightforward: When an attack hits, it causes damage...when a creature fails a saving throw, the creature suffers a harmful effect...when an ability check equals or exceeds the DC, the check succeeds.
- As a DM you have a variety of flourishes and approaches you can take when adjudicating success and failure to make things a little less black and white
a. Success at a Cost: When a character fails a roll by 1 or 2 you can allow the character to succeed at a cost. When you introduce costs such as these try to make them obstacles and setbacks that change the nature of the adventuring situation. In exchange for success, characters must consider new ways of facing he challenge
b. Degrees of Failuer: Sometimes a failed ability check has different consequences depending on the degree of failure
-Critical Success and Failure : Increase the impact of success or failre on a 1 or 20
Practices for determining advantage and disadvantage as well as practices for determining consequences of rolls with some optional ways to expand on it.
OPTIONAL RULES
Variant: Automatic Success
-A character automatically succeeds on a check with a DC less than or equal to the relevant ability score -5
- If a characters proficiency bonus applies to a check (through skills or tools) they automatically succedd at a DC 10 or less, at 11th level they auto-succeed on DC 15 or less
Also I included this rule because its optional but it does seem to address the general competency complaint some have about the d20...at least when it comes to tasks that should be relatively easy for heroic characters.
One thing noticeably lacking is a closed resolution system for multiple tasks... On the one hand I don't know if it's necessarily needed... On the other hand I think for those that want it... that the complex trap rules in Xanathar's would be a good basis for something similar to the 4e skill challenges... though I also think the skill challenges from 4e could easily be adapted to 5e.
