I run a 5e campaign, and I like rewarding my players for thinking outside the box, roleplaying well, etc. Suppose we have the following scenario:

Violet is a bard, and is attempting to intimidate a city guard while they are alone. The nearby torches suddenly dim and flicker uncertainly. Various objects shake violently and fly about the room, crashing into the walls, tables, and each other. Violet makes a wonderfully scary and venomous threat to the guard.

Violet’s use of fun bard spells and the good roleplaying was great, and I want to reward her player on the Intimidation roll.

I see two possible ways to do this:

• Grant the player advantage on whatever roll they’re making


• Reduce the DC of the check (but by how much?)

How do these two methods differ from one another? Are there scenarios when one is preferred over the other?

Just give advantage

I’ll get to the math in a minute, but the math really should be moot: there is no guidance for altering DCs based on PC actions because the point of the advantage mechanic is to eliminate the hundreds of ways of tweaking situational probability.

Advantage (and disadvantage) exist entirely to handle exactly these sorts of situations. Avoiding using it is fine if you’re into homebrewing your game rules, but if you’re wanting to just use the methods the game provides, give advantage.

The math, in very brief

Advantage is equivalent to reducing a DC by 5… sometimes. That’s the average. How much advantage is actually worth depends on what your original DC and roll bonus are, because the probability for the highest of two dice beating a target number is a curve instead of a straight line.

Advantage is the usual way

DnD 5e seldom uses situational modifiers to rolls. Advantage is the usual way for the system to describe something is particularly easy because of some circumstance. Advantage is more conventional than lowering the DC, and your players are more likely to be used to it than changing modifiers or DCs.

Advantage is more transparent

Unless you tell the player that the DC has changed, they won't know their cool plan had any effect. Advantage on the roll is transparent and serves as a good reward for playing the character's strengths well.

Advantage affects the numbers more smoothly

Having advantage on a roll squares your chance of failure. Importantly, this means failure never becomes impossible because of advantage. Lowering the DC or granting a bonus modifier is just a flat decrease in the failure chance of five percent points per point of DC decreased - and notably, this can reduce the chance of failure to zero (especially if the Bard in question has Expertise in Intimidation).

Overall, Advantage is the way to go. It's clear, it's the usual way to do it in 5e, and it changes the probabilities smoother than changing the DC.

This is partly DM prerogative, but the Dungeon Master's guide does give handy guidelines.

The DC is typically more of a fixed thing, representing the difficulty of the task (though still set by the rules or the DM). For arbitrary tasks it gives some examples such as:

Easy = 10, Medium = 15, Hard = 20

However, the DMs guide speaks of advantage and disadvantage. There it says:

They reflect temporary circumstances that might affect the chances of
a character succeeding or failing at a task. Advantage is also a great
way to reward a player who shows exceptional creativity in play.

This quote sounds like it answers your question.

Giving advantage avoids any issues of trying to add up or subtract a whole bunch of DC modifiers; it is much more straightforward.

Mechanically, I would say the main difference is that advantage is easier and provides more stable results (As your result chances go from evenly distributed, to a favorably skewed bell curve). 5e favors using advantage/disadvantage as a quick, simple, effective way to deal with temporary bonuses.

Narratively, advantage is a temporary bonus to one action, while a change in DC is a change in the difficulty of the task being attempted.

Giving Advantage means the task is harder for Violet to fail

This means, narratively, that thanks to Violet's special effects, the guard will be more likely to be intimidated by the next thing that comes out of Violet's mouth. The bonus is only for Violet's next action (or until the effect that gives Violet advantage no longer applies to the situation).

Changing the DC means the task has changed

This would mean the guard has lost their composure, and they will think everything is more intimidating/scary. In this case, the bonus applies to Violet and to anyone else attempting the same task.

As another example, building a partial bridge over a gap doesn't make jumping over easier; the jump you have to do to get across is now an easier task for everybody.

The task has not become easier, the bard just did a super good job. Because of that I think advantage is better. DC is how difficult a task is.

Here's an example of using a lower DC to intimidate a guard.

Player: Violet looks at the guard. She want so size him up to see if
he is a tough guy.

DM: Roll Wisdom (Insight).

Player: Nice, 18!

DM: This guard has a big scar over his face and looks like he's seen a
thing or two in this town.

Player: Yikes! Violet checks another entrance.

[...]

Player: Okay, Violet also sizes this guy up, I rolled another 18 on
Wisdom (Insight), does she learn anything?

DM: This guard looks nervous. He looks to his side as he seems to hear
something. A rat darts across the path. He jumps a little and quickly
looks around to see if anyone saw him lose his cool.

Player: Perfect...

Since Violet is about to intimidate a guard who is more easily frightened I'd reduce the DC here instead of giving advantage.