Mixed-Success Combat Rolls for 5E

Last week I cryptically posted a whiteboard chart to my social media. Here’s an update to that chart, with an explanation of how I’m using it for 5th Edition (and will adapt it to Apparata Kitbash later):

The concept of a “mixed” or “partial” success dice-rolling system is not new. It’s been popularized with Apocalypse World and continued in a host of games “Powered by the Apocalypse”. They use 2d6 rolls with 10-12 = success, 7-9 = partial-success and 6-or-less = failure. I like how Dungeon World describes it: “7–9 is still a success but it comes with compromises or cost.” In my version for 5E, the cost will give enemies the opportunity to attack back (and otherwise don’t take the usual turns).

d20 Mixed-Success System:

20+ 14-19 1-13
    Grand Success         Mixed-Success         Failure    

Note: I feel my players react well when I refer to a 20+ total as a “Grand Success” and the 14-19 range simply as “Success”. The psychological shift in terminology is probably effective, yet I still like saying “Mixed-Success”. Regardless, it should be treated as the standard result.

Why? How does this work?

My primary goal is to speed up combat: I’ve removed Initiative. On a player’s mixed-success or failure, enemies make a reactive attack at the end of the player’s turn. Neither side makes any additional rolls to see if they hit, just this player-facing roll of testing for success. AC is no longer used to calculate hits, but instead is used to mitigate damage (more on that below).

In practice, it means a player rolls for success and then immediately rolls for damage or not. The DM may also directly roll for damage appropriately from the enemy (occurs after the player’s completed turn).

I have not (yet) applied mixed-success to skill checks. If I do, I may use a different system because this is tuned for combat encounters.

A Comparison:

Standard 5th Edition combat goes something like this:

  1. Combat starts out with each combatant rolling for Initiative. The first on the initiative chart takes a turn. During the first round, anyone caught “surprised” skips their first turn.
  2. The player (or enemy) chooses an action to make. If that action is an attack, they typically roll a d20 and add their appropriate modifier (for a melee attack that is typically STR + Proficiency). They state their total.
  3. The DM checks the total against the enemy’s AC, describes how it hits or misses. If it hits, the DM asks the player to roll for damage.
  4. The player rolls for damage.
  5. The DM subtracts the damage from the enemy’s health and describes what occurs (especially if it dies).
  6. The player may also use a bonus action and interaction, then it moves onto the next turn (back to step 2) on the Initiative list, including the enemies on the list.

Revised Mixed-Success combat goes like this:

  1. There are no Initiative rolls. Players take their turns in their already determined “marching order”. The DM may determine enemies to have “surprise” advantage and begin with related attacks, but otherwise enemies only act reactively, at the end of individual player turns.
  2. The player chooses an action. They may make a d20 attack roll, adding their modifiers and stating their total as normal. The player then knows whether they hit or not, using the chart. Any success is a hit. If they get a “Grand Success” then they have blocked the enemies from taking any reactive actions. If they hit in the mixed-success range, they still hit, but an enemy (usually the one they are attacking) will get a turn following theirs.
  3. The player may use a bonus action, interaction and end their turn.
  4. An enemy may take a turn only If the player’s attack roll resulted in mixed-success or failure AND there is an enemy with a turn left this round (one turn per combatant per round). Usually the DM chooses the enemy the player had attacked, but they don’t have to. After that it moves to the next player’s turn.

It may not seem like many less steps, but I’ve found that removing the back-and-forth on AC checks speeds things up considerable. There are other cool implications and I also I intend to take it further with Apparata Kitbash by reducing player-hesitations while adding modifiers (more on that in a future article).

If the player does not make any sort of attack roll, mixed-success is the default for their turn. Players cannot avoid enemy actions by only using spells or abilities that automatically hit or otherwise take no attack rolls.

Monster Management:

I love the the potential for players to inherently strategize some crowd-control over their enemies.

A basic example:

Now instead:

Imagine how the players can manipulate the battlefield this way. Plus crits have a good, solid additional oomph to them!

Speaking of monsters: If a creature has legendary actions, those can still apply, or a DM can give that creature an additional turn per round after the players.

Armor Class?

Armor Class doesn’t go away with this system. Make an easy conversion for AC to mitigate damage instead of being the to-hit target. For each player and monster, calculate an AC-bonus the same way you would a stat bonus : With every even number above 10, add a bonus point. For example, an AC of 16 would be an AC-bonus of +3 and an AC of 18 would be a +4.

The AC-bonus is used to subtract incoming damage. Simple mitigation.

I admit I haven’t done hard testing on AC-mitigation for creature balance just yet. I may change it outright to whatever is above 10 (so 18 becomes 8) or use a multiplier (AC-bonus x 1.5 ??) to tweak it. For the most part I feel CR ratings on 5E monsters are pretty loosely calculated as it is. Defining encounter difficulty is an inexact science. The point is it should feel fair to your players.

Some Math:

With Apocalypse World’s 2d6 rolls, the base chance rates are 16.67% for good success, 41.67% for partial success and also 41.67% for failure. Rates change with modifiers and these numbers make sense for PbtA games. Note that in either system: partial / mixed-success stays at a static rate throughout in the middle, the modifiers just expand the greater success and crunch down the failures.

With 5E, modifiers ramp up quickly with initial character stats and then crawl upwards with level gains. I decided on a distribution that resulted in 10% failure at a max of +11 (best possible stat bonus + proficiency). The numbers may seem harsh at their base: Just 5% for Grand Success, 30% for Mixed-Success and a whopping 65% Failure. I like the psychological effect of this, because players feel like they are beating the odds (with their modifiers doing the heavy lifting). Grand Success isn’t as hard as it seems. Even a poorly rolled level 1 character in 5E is likely to be using an attack roll with a modifier of +3 or more.

I also adjusted my players down a notch in proficiency, but this is not necessary. As a DM, play around with the proficiency bonuses if you want to mess with difficulty in your campaign.