Why are there three types of crit?
How could you think this was a good idea?
Tl;dr
We use multiple crit types to activate effects with different likelihoods. This can save us a roll, allowing us to choose to compress the success check and effect check into the same roll. Half crits are more common than matching crits, full crits are the rarest of all. Advantage makes hitting crits a lot more likely.
You Gotta be Critting Me
This is the first in a series of posts about unusual and questionable mechanics in Actlite. This mechanic is a lot more entrenched than some of the other mechanics I’ve been playing around with so I expect it to stick around, but I’ve been wrong about that before! At the time of writing the rules for crits looks like this:
Crits and More
If a character rolls in a check or contest and the they succeed, they check the face values on the dice they rolled. They may have skills or effects that are activated on one of three "critical rolls" or die combinations. These are listed below
Full Crit: Rolling two 6s.
Matching Crit: Rolling two matching face values.
Half Crit: Rolling at least one 6.
An example of one of these effects is a character who inflicts the \[bleed] condition on half crit when dealing [Slicing] damage. Notice that rolling a Full Crit activates both the Half Crit and Matching Crit conditions.
There is one condition that can be activated when a character fails, the Total Failure.
Total Failure: Rolling two 1s.
Getting a Full Crit when attacking always means dealing 1 more crit damage. Otherwise, rolling a Full Crit means succeeded at your task as well as you could have. Likewise, rolling a Total Failure means you did as badly at the task as you could have. The effect of these dramatic successes and failures is up to DM discretion. Not all checks or contests will involve a great distinction between success and dramatic success.
Full crits and total failures are both always significant, unlike half crits and matching crits. Half crits and matching crits can both be used by skills to activate effects. For example, a skill might allow you to inflict 1 [bleed] when you roll a matching crit when attacking with a [Slicing] weapon. Some weapons have effects that activate with a successful half crit roll. Rather than always rolling for damage, many weapons do flat damage and rely on crit conditions to vary damage. Similarly, skill checks can rely on crit conditions to determine degree of success. Advantage and disadvantage further complicate these crits.
Advantage/Disadvantage
When you have “advantage”, roll another die during your check, pick two. When you have “disadvantage”, roll another die, pick the two lowest. Advantage and disadvantage cancel each other out, but they are also cumulative. That is, if somehow you have disadvantage on a check twice, but advantage four times, two of the advantages and disadvantages cancel out, and you get double advantage. So, you roll four dice and pick two. Because you can pick two rather than having to take the two highest rolls, you can be strategic with the effects you activate. For example, if you roll a 6, two 4s, and a 2, you may choose to lower your roll’s total from a 10 (4+6) to an 8 (4+4) in order to activate an effect triggered by matching dice if you succeed (otherwise you would get a half crit).
So it seems important to be able to know how all of these mechanics interact probabilistically! We have a couple strategies we can choose from. We could repeatedly simulate dice rolls and aggregate over our results with the monte carlo method. We could find the analytic solution by figuring out an equation for each situation (tedious, introduces some human error). Or, we could just use the combinatorics. Because dice give discrete outcomes (you never roll a 2.3525), and their probability distribution is uniform (every outcome is equally likely on a fair die), simply generating every combination and then checking them all is clean and easy. So that’s what I did. A roll of 7 or above was considered passing, as in a flat check against a passive score of 0 or an attack check against a DEFENSE of 6. Here’s the result.
Passing Score: 7
passing_matching: A matching roll that passes the difficulty score.
prob_pm: probability of passing_matching (which is passing_matching / total_rolls).
“passing_halfcrit” and “prob_phc” mean what you think they would mean, given the above.
adv_level corresponds to the advantage level, with negative values for disadvantage.
These are probabilities, not percentages, they are between 0 and 1. A probability of 0.5 is 50%. Substack apparently doesn’t have table support (!!!) so here is a pastebin with the table as a csv. You may have noticed that total failure is absent. Total failure is always going to be the inverse of full crit with respect to advantage. That is, with 0 advantage they are equally likely, total failure at -1 advantage is equal to full crit at 1 advantage etc. Alright! Now that all of that out of the way, let’s take a proper look at the data.
You’ll notice right off the bat that passing matching is generally less likely than passing half crit. Every half crit will have a 6 in it by definition, but matching dice can be something like two 2s, which is really unlikely to pass and Difficulty Score. When creating skill or effects, half crits should be considered more common than matching, both are made far more likely with advantage. The probability of a full crit is nearly tripled by advantage.
All sorts of conditions are less likely in disadvantage than advantage. In the advantage case we take the set of dice rolled and find out whether we can make half crit, matching, and/or full crit. In the disadvantage case we have to take the two lowest dice. Only then do we see what that gives us. Characters do not benefit from extra dice being rolled because they don’t get to choose the dice they get.
Let’s take a look at cases with different passing scores.
How Difficulty Score Affects Crits
Passing Score: 5
Passing Score: 7
Passing Score: 9
Note that the “passing” columns are the only ones affected by the changing Difficulty Score. The probability of half crit drops slowly, matching crit drops faster. To me, this suggests that half crit activation in combat should be a bread-and-butter damage dealer. In a non-combat situation the sort of success that a character can get on a half crit should set them apart from other characters, expressing their exceptional skill. Effects that are activated on matching crits should be more devastating or dramatic. Matching crits are more often activated either when a character has hit a full crit or when they are very likely to succeed at a check. Matching crits allow characters to show off.
Crit Doesn’t Even Sound Like a Word Anymore
In most other contexts “crit” means “maximally effective strike”. in roleplaying games it mostly means “highest possible roll”. In this system we have 3 types of crits. I don’t love that. Worse, there are two types of health, and one of them is called crit health! Half crits don’t necessarily do crit damage on an attack, but full crits do! I don’t think there is anything wrong with this mechanically, but there’s a good chance “crit” as a term is completely overloaded at this point.
In an attempt to reduce confusion, getting a minimum roll of two 1s is called a “total failure” rather than the more common “crit fail”. I will likely have to make more changes like that.
End
If you want to tool around with the code that generates this, use check_conditions() in dice_utils. You can pass in your own arguments for the passing_value or the adv_range.