13th Age RAW (Rules As Written) don't have rules for NPCs making skill checks. Most of the time this isn't necessary, but on a few GMing occasions, I felt that it would be cool to see if NPCs failed or not. I managed to come up with a few solutions inspired by Brian Slaby's post and comments from this thread I'd made on 13th Age's Google+ page. Here they are:

**Solution #1**

Solution #1 is a saving roll. Determine the NPC's probable competency at doing a task based on the following scale:

Competent (roll flat save of 6+ to succeed)

Average (roll flat save of 11+ to succeed)

Incompetent (roll flat save of 16+ to succeed)

Roll a flat save w/o modifiers, with the DC being the number in parentheses. The task has to be relevant to the NPC's capabilities -- this is the GM's call to make. A goblin would thus be competent at swinging from one bank of the river to another, but incompetent at solving a puzzle; the reverse order of that logic would apply to an insane wizard.

Example 1: A frost giant is trying to break through a thin wall. He needs to roll a save of 6+.

Example 2: The same giant is trying to break through a thick wall. Now he needs to roll 11+.

Example 3: The giant is now trying to pull himself up a ledge. This roll's difficulty for him is 16+.

Pros: It's a fast and hassle-free solution

Cons: There are only 3 bands of probabilities (75%/50%/25%). In the narrative sense, this means that failures/successes won't be as dramatically determined by the dice, which is something that I like, particularly when determining outcomes. It's also quite arbitrary.

BTW if the above is not to your liking, here's an alternative scale that you can consider using:

Competent (roll flat save of 5+ to succeed)

Average (roll flat save of 10+ to succeed)

Incompetent (roll flat save of 15+ to succeed)

The probabilities shift to 80%/55%/30%, which means monsters are generally more capable. This makes things a little harder for PCs, and possibly overall more dramatic..

**Solution 2**

In Solution #2, we use a system of Aspects similar to Fate. First, we assign our NPC an Aspect that describes what he's doing. It could be "Bashing" or "Singing". Next, we assign a modifier to this Aspect based on the scale below:

+6 = Incredible to Superhuman

+4 = Great to Fantastic

+2 = Good to Very good

+0 = Average

-1 = Sub-par to Underwhelming

-3 = Weak to Terrible

To determine if the NPC succeeds or fails, we use the following formula:

[d20 + aspect modifier + level] vs DC

Example: Let's say Joe Kobold Lvl 1 joins a singing competition. He has "Terrible Singing (-3)". The judges have average expectations (DC15).

On the first try, we roll 7 on our d20. We get 7-3+2 = 5 (vs DC15), which is a fail. Undeterred, Joe continues to sing. On the second try, we roll 19, and end up with 19-3+1 = 17 (vs DC15). Now we succeed.

Pros: Flexible, and takes into account the NPC's skill and the environment's difficulty.

Cons: Depending on how often one needs to roll skill checks for NPC, it could get tedious.

**Solution 3**

Solution #3 is similar to #2, but we use Ability score modifiers instead of Aspects. In 13th Age, NPCs do not have Ability scores, but using the same modifier scale from Solution #2, we can still roughly gauge their Ability scores' modifiers:

+6 = Incredible to Superhuman

+4 = Great to Fantastic

+2 = Good to Very good

+0 = Average

-1 = Sub-par to Underwhelming

-3 = Weak to Terrible

The formula to determine if the NPC succeeds or fails is more or less the same:

[d20 + ability score modifier + level] vs DC

Example: Going back to Joe Kobold Lvl 1 as an example, we know kobolds generally have good Dexterity, so we have DEX +2. Let's say we want to have have him leap across a narrow ravine (DC15). Rolling our d20, we get 13. That's a total of 3+2+1 = 6 (vs DC15) which is a fail. Failing forward, he slips and falls off but barely manages to cling on to the fissures of the walls. We want him to scale the walls (DC15), so we roll our d20 again, this time getting 12 for a total of 12+2+1 = 15 (vs DC15). Success!

Pros: More consistent than Solution 2 in that you only need to write down one Ability score, then it can be used across the board for a range of activities.

Cons: Aspects offer more narrative flavour than Ability scores.

### Final Note

I came up with Solutions #2 and #3 while designing really tough monsters and environmental puzzles. I didn't just want my monsters to fail or succeed on flat saves -- I wanted the dice to have a partial simulation of the process. However, based on a few mathematical trials, I've found all 3 to work pretty similarly in terms of success/fail probabilities. The pros of #2 and #3 are really that they're more flexible, but the cons are that they're less suited for those unused to quick mental calculations, which is where #1 really comes out on top. Regardless, YMMV, and since they're quite similar, just find one that works for you and stick with it. Personally, my choice goes out to #2.

Oh yeah you can do competing rolls with #2 and #3 too ;)

#### Other Links:

Brian Slaby's PD/MD method

ruemere's PD/MD method (linked to my original Google+ thread)