What Did You Expect: A Dice Math Case Study with Chainsaws!

Welcome Wargamers! Selfishly, I get to kill two birds with one stone in this article; I have been doing list research for an upcoming Warhammer 40k event and thought I would share the methods I used, and musings I had along the way. Today we’re going to dive into expected damage output of one of my favorite units, the Sisters Repentia, against a few of the more common units they can expect to see on the table!

Definitely the heroines of this story

We’ll focus on the differences in output that you can expect to see with changing the unit size as well as the Pros and Cons you need to anticipate to maximize your use. Just because we focus on a unit I choose today, doesn’t mean these principles can’t apply to your own favorite units and games! If you’re ready for some math analysis with all the complexity of “Hooked on Phonics” centered in the 41st Millennium, than you are in the right place.

The Preamble:

An essential part of good list construction in tabletop games is having a dedicated roles for your selected units, to accomplish a task. Some units are great at serving multiple roles, some armies have roles they prefer over others, and some units personify the role so well it’s hard to use them any other way. We could spend all day talking about the differences (and different opinions of the strengths of each roles in general), but a role that can’t be ignored is the classic “trade piece” or “missile” unit. Not expected to come back alive they are expected to do their job in the brief time they could be on the table, either buying you valuable time, grabbing a dangerous piece of ground, or removing a strong opposing unit (or all of the above).

For those of you that may not have heard, Sisters of Battle are real good in Warhammer 40,000 in the GT Nephilim ecosystem. With very strong secondary objective options, units costed to move, and the ability to take luck out of the equation periodically, you can often overwhelm your opponent’s efforts with what would appear to be relatively simple units. Sisters Repentia are an important piece of that puzzle and sum up the “trade” unit archetype really well; I expect them to accomplish a task or two before being put down.

Sisters Repentia and Crimson Fist Allies staring down a depraved enemy of Mankind

So just what makes them a staple of so many lists? Let’s take a look:


  • High damage output in melee, and take faction melee buffs particularly well
  • Great target for granted Obsec from the Dogmata, for stealing objectives
  • Ability to “fight on death” using Command Points
  • A cheap upgrade character that allows for advance and charge, and +1 to wound
  • Cheap (notice the trend here) for what they accomplish
  • Grant you Miracle Dice when the unit is killed, provided it’s not a morale test


  • Limited to damage only in the fight phase
  • Die to small arms fire or weak melee attacks if left out of position
  • Very susceptible to quality overwatch
  • Top-end performance is dependent on their native re-rolls
  • Can be quite CP hungry, between pre-game movement options and fighting on death.
  • Potential for premature loss of the unit in the Morale phase of the game when taking casualties

All of these factored together, you have a cheap and cheerful unit that has tremendous output, the ability to steal objectives with temporary Objective Secured, and the tenacity to sometimes live despite the odds. Even better, if your opponent’s not careful in the Fight Phase you can take a unit down with you, and be rewarded with a Miracle Dice for the trouble. You don’t have any wargear options in the unit (bigger chainsaws when, GW?), so how do we get the most of out them?

By the Numbers:

If you look at the Sisters of Battle army lists that are doing well competitively, they tend to have a few small units of Repentia with either 5-6 sisters each in 2-3 squads, or two squads each with 8 or 9 models. I find myself in the “more chainsaws, more good” camp personally, but at a minimum these squads need to be able to handle a hard target. However there are some notable advantages for running a smaller unit; they’re easier to kill outright so you are rewarded with Miracle dice, easier to hide, and cost you fewer points for a “one shot” unit.

The Common

Given that there are distinct advantages of either a small or large unit, what should we expect from squads of that size?

We’re going to set some basic assumptions first, and we’ll cover additional variables as we go;

  • The Repentia will be under the “The Passion” Sacred Rite army rule, so that their unmodified 6’s to hit in close combat cause additional hits.
    • If you’re playing a melee-centric sisters army, this is often the best choice.
  • Armor of Contempt will be active for the target if they are a Marine Equivalent (MEQ) or a Terminator Equivalent (TEQ)
  • Repentia weapons give themselves -1 to hit in close combat, and “Zealot” allows for re-rolling failed to hit rolls if they charge, were charged, or were Heroically Intervened. This is a very powerful ability.

First, let’s address the elephant in the room, and that’s the fact that your army sub-faction choice will impact the results. Assuming the target is…well….anything, there is a clear winner here; the Order of the Bloody Rose (shocking, I know). There’s a reason the extra attack, and improved armor penetration are all the rage for the Sororitas, and it will show why quickly.

Don’t believe me? Here’s a great example first victim, a 5-model unit of Space Marine Equivalent (T4, Two Wounds, a 3+ Save, and Armor of Contempt). I’ve gone ahead in unitcrunch.com and plugged the previous assumptions in for a unit of 5 Bloody Rose Repentia and a unit of 5 that are non-Bloody Rose;

Barring any unusual saves, against MEQ Bloody Rose Repentia average one point of damage per initial attack!

There is a non-subtle difference in the expected damage outcomes of the two units, and it comes down initially to sub-faction choice. The Bloody Rose unit can expect to wipe out their foe handily by doing 10 or more unsaved damage 89.3% of the time, meanwhile the less effective option can expect to do 10 or more unsaved wounds only 36% of the time. In fact their mean damage is almost 100% lower than their counterpart.

The current motive-power to “just play Bloody Rose” is already high enough and probably warrants it’s own discussion, so let’s look at some of the other factors that can affect performance. Here’s the same unit, just bigger, taking out their prayer-fueled rage on the same MEQ;

About 27 damage inflicted on average

Unsurprisingly, there is a less than 0.02% chance to not kill the target. And in fact, you could expect to kill most of a 20-model unit of MEQ quite handily. While Space Marines are the preferred enemy of these chainsaw enthusiasts, let’s try something a bit tougher. Let’s test our subject’s into a unit of Terminators (T4, 3W, 2+, 5++, and Armor of Contempt);

Still quite effective, but the expected damage decreases against targets with invulnerable saves

This is a very respectable output for a cheap unit, but what if you REALLY need those 10 Terminators dead? You’re going to have to pull out all the stops. So what does it look like at full potential? Let’s add the following into the mix:

  • +1 Attack from War Hymn
  • +1 to wound rolls from a nearby Repentia Superior
  • +1 Damage on unmodified 6’s to wound
  • 6’s to hit will cause an automatic wound
  • Re-roll failed wound rolls from Morvenn Vahl or a Palatine
Math be damned, re-roll it all!

With every buff under the sun Repentia can hit well above their points investment, but it’s up to you the player what role they’ll serve for you. You can create a very effective glass cannon unit to try and sunder all opposition, or rely on their very capable output in small numbers to trade up and secure the advantage. You’ll get more mileage against models with two wounds, but don’t be afraid to chase down light vehicles, characters, and even Armigers/War Dogs!

These results aren’t unique to only Repentia, so let’s look at another comparable unit; Blood Angels Death Company. To keep things fair we’re also going to give them just about every buff they can grab:

  • Assault doctrine from Sanguinary Priest (+1 attacks)
  • Chapter Master (re-rolls to Hit)
  • +1 to hit from Astorath “Mass of Doom” (mitigates Thunder Hammer -1 to hit)
  • +1 to hit from Sanguinary Ancient
  • +1 attack from Shock Assault
  • +1 attack for Black Rage
  • +1 to Wound from Blood Angel Chapter Tactic

Let’s see how a unit of 9 Thunder Hammer Death Company fares into the same Terminators (T4, 3W, 2+, 5++, and Armor of Contempt);

Very comparable damage to the Repentia

Accomplishing a similar role, the Death Company produce very similar results into most targets! They have greater threat range than Repentia, and improved defensive stats, but they pay for that heavily with a points premium. There are many examples of trade units across most armies in the game, but it’s up to you to maximize their potential.

The Bad Matchups

Unfortunately, there are also hard targets that really mess with your output. A unit of 5 Harlequin Skyweaver Jetbikes for instance, as they turn off your re-rolls to hit, and have a 4+ invulnerable save natively.

Keep in mind, this could be even worse with good luck re-rolls, a 6+++ FNP, or a 3++ Invulnerable save!

Even the larger unit doesn’t reliably kill every clown-bike, and would need additional attacks or aura’s to get the job done. While you likely kill a few, it’s hard to represent additional damage avoidance through the use of Saedath “Luck of the Laughing God” dice, making this a risky engagement that may cost you your unit prematurely.

Invulnerable saves are a big barrier to causing your maximum damage (duh), but most of your damage loss is actually at the “hit” stage of the die rolls, since you don’t get another try to turn failures into bonus hits. The positional advantage that Harlequins often have can make this an extra risky proposition, so be careful picking a fight with the clowns.


  • In most cases against MEQ targets without an invulnerable save, you can calculate Repentia output along a 1:1 relationship with the number of attacks coming from the unit
  • Against TEQ targets with an invulnerable save, you can estimate the total amount of Repentia damage dealt as 2/3 of the number of attacks you will make.
  • Target selection is key, make sure to layer your buffs if you need to kill a harder target!
  • Your main barriers will be abilities that shut down your re-rolls to hit, gate your wound rolls to a 4+ or better, or abilities that cause you to be -1 Damage.

Better understanding the expected probabilities around your units’ performance can give you an edge in your decision making, as well as promote creativity in army list building. Take the time to reflect on the units you enjoy playing and you may find your newly grounded expectations challenge your foes!

That’s all until next time, but what did YOU expect?

I hope you enjoyed this breakdown, and this sparked some ideas for your own games. If you have any unit examples you’d like for me to test in a future article, feel free to send me your suggestions! Drop a comment below if you’d like to see more content like this, and check us out on YouTube or join the community on our Discord!

YouTube Channel: https://www.youtube.com/channel/UCtfbXR181RLbqW5B2Huwz4w
Discord Invite: https://discord.gg/a9hAPtH
Patreon Page: https://patreon.com/lineofsightwargaming

Published by Kenny Bush

Tabletop Games Enthusiast in the Pacific Northwest, a part of the Line of Sight Wargaming crew. Mostly musings and treatises' on all things Warhammer, Conquest, Blood Bowl, and skirmish games!

Leave a Reply

%d bloggers like this: