Probability and Your Army I: Dice Mechanics in SONG

This article is up to date with Version 1.5 of the ASOIAF Rulebook

The hit HBO show transformed A Song of Ice and Fire from a series of niche fantasy books into a cultural phenomena almost overnight. It’s really no surprise that the miniatures game has attracted a broad audience including many people who have never played a tabletop war game before. I think this is a fabulous game to start getting into the hobby as the rules are (relatively) straightforward but it can still be confusing to try to analyze the effectiveness of various units. What do all these numbers mean? Who is going to win in a fight between Lannister Guards and Stark Sworn Swords? How much worse is a 7+ Morale score really?

If you are new to the game you’re probably making a lot of guesses. That’s fine. Many people will play the game that way. You learn through experience what works and what doesn’t and develop “gut feelings” about whether a new unit is good for your playstyle. But my goal with this article is to give you some tools to help you make those decisions before you ever get to the table. Simple math allows veteran wargames to make informed decisions and take calculated risks both on and off the battlefield. It’s a fantastic tool for improving your skill at the game.

The most basic mechanic in SONG is the six-sided die roll (in gaming circles you will see this referred to as a d6 or rolling 1d6). A single die roll against a target number is used for attack, defense and charges. If your roll meets or exceeds the target number it is a success. This means that lower target numbers are better which may be unintuitive if you’re coming from another game system.

You probably know that each side of a 6 sided die has an equal chance (1 in 6 or ~16.67%) of coming up when the die is rolled. You can calculate the probability of meeting or exceeding a specific number by adding up the chance to roll each successful outcome. I’ve done this on the table below.

Attack, Defense and Charge Probability (1d6 rolls)

Result Probability
1+ 100%
2+ 83.33%
3+ 66.67%
4+ 50.00%
5+ 33.33%
6+ 16.67%

Now let’s take a look at how to apply this knowledge to a unit.

Lannister Guardsmen Unit Card

Lannister Guardsmen unit card from the ASOIAF Wiki

These are the Lannister Guards from the Stark vs Lannister Starter Set, a solid reliable infantry unit that forms the backbone of many Lannister armies.

The numbers on the left side of the card are the Guards’ stats:

  • Speed (foot icon): 4
  • Attack (sword icon): 4+ (6/5/3)
  • Defense (shield icon): 3+
  • Morale (flag icon): 7+

Speed is the simpliest of these. It is a flat value except when charging. Units may Maneuver up to their speed or March up to twice their speed during their activation.

To execute a Charge the player must roll 1d6 and add the result to the unit’s speed. The final value is the maximum inches that the unit may move. Hopefully it’s enough to reach your target! Failing a charge can be a disaster as it leaves you open to counter attack and can throw off your entire battle plan.

Using the probability table above you can easily calculate how likely a charge is to succeed or fail. If the Lannister Guards are 8 inches away from some Stark Sworn Swords then you can take 8 (Total Distance) - 4 (Speed) = 4 (Target number). You need to roll a 4 or better. Consulting the table you see that you have a 50% chance to succeed. That’s pretty good, right? No. It really isn’t. Would you gamble your whole plan on a coin toss? If not then you probably shouldn’t take a 50% charge either. Try to get closer.

Attack is a bit more complicated. You now know that if 4+ is the target number then the Guards have a 50% chance to hit, but what about (6/5/3)? Those are the number of attack dice you roll depending on the current health of the unit. At full ranks, the Guards attack with 6 dice. At two ranks they attack with 5 dice. And at one rank they only attack with 3. How do we figure that?

You can multiply the hit probability by the number of dice to get Average Hits:

  • 0.5 (50%) * 6 (dice) = 3 average hits
  • 0.5 (50%) * 5 (dice) = 2.5 average hits
  • 0.5 (50%) * 3 (dice) = 1.5 average hits

Note that these are averages. You may roll 6 hits. Or no hits. Or anything in between. But over many thousands of rolls the most likely outcome is 3 hits. While it is exciting to think you might roll and kill six enemies, your planning and analysis really needs to consider average results if you want to make good decisions.

Due to the way SONG units change in effectivness as they take wounds another useful metric is what I call the Lifetime Average. You can calculate this by taking the average of hits at each rank:

  • (3 + 2.5 + 1.5) / 3 = 2.33 lifetime average

This value is useful for comparing units and list building before a battle. No matter what you do, your units will take damage and some units will lose effectiveness much faster than others. The 2.33 lifetime average is very close to the Guards maximum offensive potential which tells us that they are weak but consistent hitters.

But wait, those hits don’t equal kills!

Defense is pretty similar to attack except the number of dice that you roll is the number of hits you are defending against. The Guards’ defense of 3+ gives them a 66.67% chance of blocking each hit. That’s one of the best values in the game!

Let’s say that two units of Guards are engaged in a training exercise. The first unit attacks and rolls their average of 3 hits. Now the defender must roll 3 defense dice. How many hits are they likely to block?

  • 0.6667 (66.67%) * 3 (dice) = 2 blocks

So the attacking Guards will probably only manage to deal one wound. It’s going to take a really long time for two Guard units to wear eachother down.

That’s where Morale comes in. The Guards’ Morale is a 7+. You can’t roll a 7+! Well, you can, because in SONG we check morale by rolling two dice (2d6) and adding the results together. The morale and panic rules have been greatly simplified in the 1.5 Rulebook Update and those are the rules I will be discussing here. If you are still playing an older version of the game you can find the new Rules on CMON’s ASOIAF Website under the Rulebook tab.

To make a Morale test you roll 2d6 and compare the result against your Morale stat. A combat Morale test is called a Panic test because the consequence of failure is that some of your soldiers panic and flee from the battlefield. The rules are very good about distinguishing between Panic tests (which cause Panic) and other types of Morale tests (which have different consequences). Pay close attention to this. Many people get confused and think their units take wounds after every failed Morale test. That’s not true.

If you fail a Panic test, your unit takes 1d3+1 wounds. The d3 is the mysterious white die that came in your starter set. If you look closely at it, you will see that the faces are labeled 1, 2, 3, 1, 2, 3. This die was added late in the game’s development to prevent arguments about how to get 1-3 out of a standard die, a topic which is, apparently, quite divisive in the wargaming community.

Anyway, what do the probabilities look like when rolling two dice?

Morale Results (2d6 rolls)

Result Success Failure
2+ 100% -
3+ 97.22% 2.78%
4+ 91.67% 8.33%
5+ 83.33% 16.67%
6+ 72.22% 27.78%
7+ 58.33% 41.67%
8+ 41.67% 58.33%
9+ 27.78% 72.22%
10+ 16.67% 83.33%
11+ 8.33% 91.67%
12+ 2.78% 97.22%

This table is pretty easy to use. You can just scan down to the Result that matches your unit’s Morale stat and then across to the Success and Failure columns.

Our Lannister Guardsmen have a Morale of 7+ which gives them a 58.33% chance to pass a morale test. That’s not terrible.

Panic Losses (1d3+1 roll)

Result Probability Losses
1 33.33% 2
2 33.33% 3
3 33.33% 4

This one is pretty easy. The d3 only has three possible results. If you fail a Panic test you have even chances of taking 2-4 wounds.

The new rule is a big improvement for Guardsmen who previously could take up to 7 wounds on a bad roll. It made things slightly more dangerous for units with good (low) morale values as they are likely to take more damage than before when they fail. However, their chance of failure has NOT increased. Umber Berserkers still have a 91.67% chance to pass their Panic tests. It’s just the other 8.33% they have to worry about.

Now that we know how Attack, Defense and Morale all work let’s see how we can use this information to simulate a combat between two units.

Stark Sworn Swords Unit Card

Stark Sworn Swords unit card from the ASOIAF Wiki

These are the Stark Sworn Swords, the basic infantry of the Stark faction and also available in the Stark vs Lannister Starter Set.

Despite filling a similar role in their respective armies, these units are quite different. The Stark Swords are faster with Speed 5. Both units hit on a 4+ but the Starks have a much stronger dice pattern (8/6/5 to 6/5/3) which means they will generate more hits. Their defense is only a 4+ which we know is 50/50 but their morale is slightly better at 6+.

Let’s calculate average hits for the Stark Sworn Swords:

  • 0.5 * 8 = 4 hits at full ranks
  • 0.5 * 6 = 3 hits at two ranks
  • 0.5 * 5 = 2.5 hits at one rank
  • (4 + 3 + 2.5) / 3 = 3.167 lifetime average hits

So they do hit a bit harder but let’s see what happens when they attack the Guards.

  • 0.6667 (guard defense) * 4 (sword hits) = 2.668 blocks

That’s interesting. Despite their better attack stats they’re still probably only dealing one wound to the Guards. Two if they get lucky.

Likewise when the Guards attack the Swords:

  • 0.5 (sword defense) * 3 (guard hits) = 1.5 blocks

The Swords are probably taking 1 wound and have a 50% chance of taking another. So in a prolonged engagement between the two units the Guards will probably inflict more raw damage despite their weaker attack stats. Bet you didn’t see that coming. Defense is good!

How is this balanced? Morale and Panic.

When the Guards take a wound they have a 41.67% chance of failing their Panic test and taking 2-4 more wounds while the Swords have only a 27.78% chance. That one point of morale makes a pretty big difference.

Both units also have an additional ability on the right hand side of their card.

The Lannister Guards have Lannister Supremacy which says “If this unit is attacked and passes its Panic Test, the attacker must make a Panic Test with -2 to their roll.”

Ouch. That sounds bad. So when the Swords attack the Guards and deal a wound there is a 58.33% chance that the Guards will succeeded at their Panic test and trigger Lannister Supremacy.

Many abilities in SONG apply modifiers to die rolls such as the -2 from Lannister Supremacy. You roll the die and then add or subtract the modifier from the result before comparing to your target value. For the sake of probability you can also think of these modifiers changing your target value. In this case the Stark Swords would need to roll an 8 or better on the check. (8 - 2 = target value of 6 Morale) which changes their outcome on the table significantly.

Also note that Lannister Supremacy applies when the Swords are attacking the Guards. This is an extra Panic Test that happens out of sequence. They have to make another one if the Guards attack them and deal wounds. Two Panic Tests a turn! Ouch! This sort of you-get-hurt-for-hitting-me shenangins is a theme of both the Lannister and Baratheon factions so watch out for it.

This makes things look really bad for the Starks but they too have a special ability that is quite powerful: Stark Fury.

Stark Fury says “Before rolling dice, this attack may gain +1 to Hit and Critical Blow (Rolls of 6 deal 2 Hits). If it does, after this attack has been completed, unless this unit only has one remaining rank, it suffers D3 Wounds.”

Note that Stark Fury says you “may” gain the benefit. That means you get to choose during each attack whether to trigger the ability or not. Some abilities say you “must” use them. That means you don’t get a choice!

What does Stark Fury do for the Swords? +1 to Hit and Critical Blow.

+1 to Hit is a modifier for their attack dice. You add 1 to each die before comparing it to the target value. This effectively changes the Swords’ Attack stat to 3+ or 66.67% chance to hit on each die.

They also gain Critical Blow. I’ll discuss special keywords in a future article but the short version is that Critical Blow gives each die a 16.67% chance to roll an additional hit. So the Swords could roll 16 hits! Well, they could, but remember what I said before about planning around averages.

The Swords’ new attack average looks like this:

  • 0.6667 (3+ Attack) * 8 dice = 5.3336 hits
  • 0.1667 (crit blow) * 8 dice = 1.3336 extra hits

For a grand total of 6.6672 hits. That’s a big improvement over 4. Figure 2-3 extra hits in each attack.

  • 0.5 (guard defense) * 6.6672 hits = 3.3336 blocks

The swords are now dealing 3-4 hits to those guards, doubling their damage output. However, they are also taking D3 wounds themselves unless they are down to one rank. Taking wounds to deal extra damage is a Stark theme. You will see these sorts of abilities on a lot of their units and characters.

There are plenty of times to use this ability even though it will hurt your own unit. Guards are probably one of the worst targets for it and, as you can see, it still comes out to a pretty even trade. Against some Freefolk with their abysmmal 6+ armor? Yes, please. Also once you get down to 1 rank there is no downside. Fury away. Not using it is just giving up free damage.

That brings us to the end of this first segment. We’ve looked at the basic mechanics of Attack, Defense, Morale and Charging as well as some simple abilities and discussed how they effect the outcome of battle. In a future article we will take a closer look at keywords like Critical Blow and the impact of rerolls (from charging or spending tokens).