With both grenades getting new profiles in 10th edition, it’s time to revisit one of our earliest questions: which grenade should I throw at what?
Of all the special weapons, grenade launchers are the perhaps the quintessential utility weapon – not the best at anything, but able to flip between anti-infantry and anti-armour duties. If you value flexibility above all else, you’re likely taking as many of these as you can.
The frag and krak profiles differ significantly (unlike plasma, for example, where the alternate profile is just a riskier upgrade), which means that they offer us choices – in most situations, there will be a right choice and a wrong choice. Not necessarily game-changingly so, but it’s always good to maximise our damage output (and on very rare occasions, know how to minimise it). So let’s take a look at how the profiles compare, and which one should go into which target.
BASICS
Frag provides d3 shots at S4, AP0 and 1 damage; krak is a single shot, S9, AP-2 and d3 damage. Both are fired at BS4+. If we take the mean average of shots (frag) and damage (krak), it’s 2 in both cases. So over time, the krak grenade is always the better generic option.
We can show an attack sequence as number of attacks x chance to hit x chance to wound x chance to beat the save x damage. Using the mean averages, frag is 2 x 0.5 x W1 x S1 x 1; and krak becomes 1 x 0.5 x W2 x S2 x 2. For both, the combination of shots, chance to hit and damage resolves to 1. This means that the only difference between them are the wound and save rolls, and at S9 and AP-2, krak grenades always have the advantage (outside of some very fringe scenarios). From this perspective, we should always fire krak grenades.
BLAST
There are a couple of additional factors to consider. The first is that frag grenades also have Blast. For our purposes, this means that for every five models in the target unit, the average number of shots goes up by one. If we fire at a unit of twenty, for example, frag has d3+4 shots, averaging 6. At what point does weight of fire push frags ahead of kraks?
[Here we have toughness on the left and save along the top. The numbers in the table indicate how many models would need to be in the target unit to make frag the more damaging option. A star indicates that frag and krak are balanced at this point.]
Into a sufficiently numerous target, frag can be the better option. Into a unit of twenty, for example, frag is the way to go against anything with a 5+ save, up to T7 (partly because T8 acts as a cut-off point, where frag drops to wounding on 6s). Into a unit of twenty, frag averages 6 shots, making it three times more effective than at baseline. This helps to counteract the better strength and AP of krak, but only to a point.
SINGLE-WOUND TARGETS
We should also bear in mind that, so far, we’ve been looking at the total damage output – in effect, treating two damage 1 shots and one damage 2 shot as the same thing. Into multi-wound targets, for our purposes here, it’s roughly the same thing. But into single-wound targets (which also tend to be low toughness, poor save, where frag is generally more useful), the additional damage of the krak grenade is lost, whereas the multiple shots of frag remain relevant. Let’s look at this again, but specifically for targets with one wound.
Now, this table is potentially a bit misleading. Remember, it’s specific to targets with one wound – whilst it’s possible, it’s pretty unlikely that we’ll ever encounter a unit of 20+ T8 models with a 2+ save and a single wound each. So whilst frag would be a reasonable choice in that situation, it’s not going to come up often.
What we do see here is that frag is a better option into guardsmen (at any unit size), and is a good choice into units of 10 up to a 3+ save (again, as long as they have just one wound, so not marines). Grenade launchers allow us to select a firing mode on the fly (rather than committing to a single option pre-game), so frag has its uses, but so far, they appears to be pretty limited.
CHANCES
The other way to look at grenades is to ask: what’s the chance that I kill a certain number of enemy models. For example, a krak grenade can only ever kill one model, but does enough damage to potentially kill a terminator; and whilst a frag could kill a terminator, it could also take out as many as three guardsmen.
[With frag, we’re factoring in the chance that we even get three shots in the first place, let alone kill a guardsman with each of them. As we move down, we’re then considering the chance of getting three shots and killing with two, plus the chance of getting two shots and killing with both; and so on. Something similar applies to frag and marines, but it’s more limited.]
On a shot-by-shot basis, krak always has a better chance to land a kill. This is true even into guardsmen, where a frag will fail completely 62% of the time, compared to the krak’s 58%. The frag does offer a slight chance of multiple kills into guardsmen, but it’s long odds and probably best saved for extreme situations. If we want our shots to count, stick to krak.
YES, THE NUMBERS ARE DIFFERENT
There’s an interesting maths anomaly here. The second table (looking at the effect of blast on single wound targets) suggests that frag is the better option into guardsmen at any unit size; but the last table (chances of any particular outcome) suggests that we should always use krak if blast isn’t a factor. Why is that?
When we were looking more generally at blast, we were using averages (because it’s simpler for bulk calculations), giving frag two shots every time (and krak two wounds, although only one counts into guardsmen). That gives frag a slight edge (44% against 42%).
But when we looked at individual shots and chances of specific outcomes, we factor in how unlikely it is that frag can convert three shots, pulling the overall result downwards. The broader averages give frag a 44% chance of a kill, whereas as the more nuanced outcomes drop that to 38%. This is also true of the krak’s damage output (also d3), but because that’s the last roll, it affects the outcome differently – we’ve already beaten the save, and are just determining how much damage is caused. And against marines (for example), two of the three possible outcomes still result in death.
CONCLUSION
In the end, what have we learnt?
Without blast in play, krak out-performs frag into everything
Into units that trigger blast, frag may be the better choice, depending on unit size (and wounds)
With these profile changes, krak has become the general purpose grenade. It’s the go-to option into most multi-wound targets, unless they come in large units; and its better into some single-wound targets too, although frag becomes more useful here.
Blast adds an addition moving part to grenade calculations – it’s no longer enough to look at the target model; we now need to consider the unit size as well. But we can at least suggest that we should use frag into guardsmen (increasingly so as the unit size increases) and krak into marines, which is a good starting point (especially if you don’t want to be referring to tables during the game). Whichever way you go, may your d3s always roll hot.