Advantage (and disadvantage) debuted in the May 24th D&D playtest as a game mechanic simulating a creature having an edge (or a hindrance) to an attack, task, or other effort. Prior to the playtest release, the design team experimented with several methods of achieving advantage/disadvantage. Each had their strengths and weaknesses.
Ultimately we decided we wanted to test an aggressive version with the initial rules: When you have advantage on an attack or other suitable d20 roll, roll twice and use the higher result. (Or, roll twice and take the lower result if you have disadvantage.)
One of the potential drawbacks we worried about was the mechanic’s novelty. Was it too wild a twist on player expectations? And, possibly too significant an actual mathematical bonus (or penalty)?
On the other hand, possible strengths of the mechanic include the very same two points: it’s a novel, exciting way to model having some kind of an edge (or hindrance), and the effect is big and meaty enough to really matter when it does apply.
An even more important strength of the roll-twice method is to reduce on-the-fly math at the table. A numerical mechanic requires a player to add at least 3 numbers together with each roll: the roll result + an already-calculated attack bonus (or ability modifier) + the advantage bonus (a +2 or +3, say). Everyone can do this sort of math of course, but each additional number that’s added or subtracted makes the calculation slower, and over the course of play, slows the game. Math is hard.
Finally, an obvious strength of the current advantage system is simply that it’s fun to roll dice.
Now the playtest is out. Those of you running Caves of Chaos and the pregenerated characters are using the mechanic. A surprisingly high number of you (our survey pros tell us) filled out and returned the survey included with the release (thank you). We were excited to see a greater than 70% approval rating for the current mechanic.
Of course it’s early days, and this is a playtest after all. We already know we need to tweak advantage/disadvantage a bit. At the very least, we need to very carefully think about appropriate places to apply it, and more importantly, places where its application is just a bad idea. In fact, that later point is important. While dice rolling is fun, too much dice rolling isn’t.
For instance, consider a spell that could inflict blanket disadvantage to a creature for a minute. What if that creature has a claw/claw/bite attack routine? Is suddenly becomes too many dice to ask the DM to roll. Imagine if that same spell applied to a group of monsters for a minute. Even worse. Likewise, awarding blanket advantage to monsters encountered in large numbers can also quickly become a pain.
Going forward, a design and development rule of thumb might be something like (what Rodney Thompson said to me over the cube wall between our desks): a player or creature should (generally speaking) expend an action to gain advantage or bestow disadvantage. I couldn’t agree more. In your playtests, try that as a guiding principle, and see how it works out.