In my opinion, the so-called ‘Rule of Cool’ is one of the things that makes roleplaying games so wonderful. However, as with many other awesome things – like chocolate, beer or naps – it has the potential to cause real harm if used too much or too loosely.

If you’ve never encountered it before, the Rule of Cool states that the rules – whether they be those of the game or reality itself – can be bent or even outright broken if service of something really awesome. View it as the grease that helps the wheels of fantasy adventure to spin without the friction of realism slowing them down too much.

For example, the Rule of Cool is what waves away the fact that the rogue should really have suffered a splintered femur when she dropped down onto her target from the rooftops. It’s what allows the cleric to glow when she confronts the dread vampire lord, despite not knowing the Light cantrip. Ultimately, it’s the reason that so many castles, towers and villainous lairs are lit by huge chandeliers secured with easy-to-reach ropes.

Used correctly, the Rule of Cool can make players feel badass and immerse them in a gameworld where anything is possible.

However, there are two ways in which it can go badly wrong – when players begin to abuse it and when the DM is inconsistent in applying it.

I encountered this first issue early on in one of my current 5E campaigns the party was attacked by plague-ridden raiders that hid their ruined faces with elaborate wooden masks. The druid was badly inured and cornered by one of the attackers but asked if she could use Druidcraft to cause thorns and vines to sprout from his mask, blinding and distracting them.

One successful attack roll later the raider had blood streaming from his face and was flailing around in panic. By the letter of the law Druidcraft shouldn’t be able to cause damage or inflict negative conditions, but invoking the Rule of Cool allowed us to ignore this in exchange for a nice little slice of drama, badassery and extra flavour for the druid’s powers.

In an attempt to make the moment suitably dramatic, I had probably overcooked the spell’s effects, handing out 2d6 of damage and a temporary blind – far too much for a cantrip. This began to cause problems when the druid started to try and use the attack – one that she had portrayed as the product of desperation and luck-  on a more regular basis.

Such an attack is very situational, not very many enemies rely on wooden armour or weapons, after all, so the actual impact on game balance wasn’t very significant. The issue was that it was taking something that should have been an exciting one-off and made it commonplace.

Think of the scene in The Two Towers where Legolas rides an orc shield down the stairs in Helm’s Deep, firing a longbow as he went – it was incredibly badass, right? But if he repeated the same trick in every fight, how long would it remain cool? How long would it be before the audience began questioning how plausible the manoeuvre actually was?

One way to avoid an over-reliance on rule of cool tricks is to try and keep them somewhat balanced. In the case of a rogue trying to leap off the rooftops and land dagger-first on an unsuspecting foe, for example, I would want to allow the player to potentially pull it off without killing themselves at the same time and potentially throw in a slight damage boost (because death-from-above-ing is the very definition of rule of cool).

At the same time I would want to make sure there was a real risk or other downside involved, such as making the player take fall damage but having half of it absorbed by the target on a successful hit.

Beyond trying to balance unexpected actions so they don’t become too overpowered, it’s also useful to just have a conversation with the players and let them know that what they just did was a one-off, and that they shouldn’t make a habit of it. This is what happened with my druid, who accepted the hints that maybe she shouldn’t be relying on that one power too heavily and agreed that I could nerf its damage if she wanted to use it again.

The part where you discuss this is also important, because failing to do so can lead to the second major cause of Rule of cool problems – inconsistency in DM rulings.

This will always be an issue as whether or not to let the rules slide is an entirely subjective DM choice that will depend on everything from the pace of the session to how much bending of the rules is needed to let the player do what they want.

Some groups will always play to the letter of the law and won’t give two hoots to how impressive an impossible situation could be with a little bit of interpretation. Others are incredibly loose and free-flowing, with the PHB and DMG very much used as guidelines that always take the back seat to the narrative and players’ power fantasies.

No matter how you treat dalliances with the Rule of Cool, however, it’s important that you are consistent in how you apply them. If you allow one player to constantly get away with warping reality through she sheer power of awesome, throwing the rulebook at another player every time they want to so something outside the exact scope of the abilities can be infuriating.

As simple as the guideline sounds, it can actually be extremely hard to stick to. Whether they admit it or not, every DM will prefer some characters and some players to others. I doubt that any of us can claim that the well-characterised Bard isn’t more likely to benefit from a convenient bending of the rules than the min-maxed killing machine with the personality of a kettle.

This can actually be one of the real advantages of the rule of cool. Generally the actions that are trying to invoke it will not only be badass, but will organically sculpt a character’s personality. Glowing with divine presence isn’t exactly going by the letter of the law, but it can grow the cleric’s connection and relationship to their god more than any number of by-the-book Channel Divinities.

Tips for players:

• You may be surprised by how much your DM lets you get away with if it’s not too game-breaking and is fitting for your character
• Never rely on the Rule of Cool. A DM can generally tell if you’re taking advantage, and we have a terrible habit of sticking rigidly to the rules if it helps us teach a lesson
• Mechanical advantages are nice, but the biggest benefit of invoking the Rule of Cool should be having your character do something awesome

Tips for DMs:

• D&D 5E very explicitly says that the rules are there for you to interpret, modify and ignore as you wish. Don’t be afraid of changing things up if you think it’ll work out for the best
• With that in mind, ignoring the rulebook on a whim can leave the players feeling unsure how your game and your universe actually function, so make sure you’re consistent
• Balancing on the fly is fine, but remember that there’s nothing wrong with correcting an earlier ruling if it ended up being hugely over/underpowered