Grey Knight Rumours and the return of Instability Checks?

In case you haven't seen the latest round of rumours circulating about the Grey Knights, head on over to BoLS where they will bring you up to speed.

There are a couple of interesting quotes that are relevant to both daemon and chaos space marine armies.
Firstly is the concept of daemonic instability looks like it might be about to make a return. Even back in the days of Realms of Chaos, daemonic instability was there: it is only recently that this rule seems to have been removed from the w40k system. In brief, daemons suffer from instability as they are not of real space, their forms being created and held together by the will of the daemon involved for a time (of course, they don't suffer such instability on daemon planets or locales near the eye of terror). In the old system, opponents could cause daemons to take an instability test (read: leadership test) if they whittled down their numbers significantly during a shooting phase, or combat phase. The amount the daemons player failed this test by would then be the number of daemons that returned to the warp in shock! Now whether this mechanic will be the same or not remains to be seen. But its looking like daemons are going to suffer if they're paired up against grey knights in a game!

And then there is something called "daemonic infestation" which makes the daemons more resilient to such instability checks. I've no idea how that would work or what it generally is referring to. Could be exciting!

The other nugget contained in there is that chaos icons (whether daemons or chaos space marines) somehow interfere with the grey knights deep striking. Sounds interesting and could be a boon for countering some of their tactics against both daemons and chaos space marines.

Finally, there's also talk of specific terrain suited to the grey knights. The could be very entertaining!

As a daemons and chaos marines player, I am worried about the power level of the grey knights. I hope they (the designers and play-testers) include checks and balances so that players such as myself don't get turned off. But I can also see myself purchasing a few squads of grey knights myself as I've always liked their background since the Realms of Chaos era.

Statistics: How Many Nurglings?

A full discussion of daemon troops wouldn't be complete without those naughty little nurglings. I have admittedly struggled to find a place for them in my mixed daemon forces (not so mono-Nurgle lists with Epidemius). But if they are to have a role, then is should be analogous to ripper swarms: a screening unit and a tar pit. Screening is tough to evaluate and it clearly follows the rule of thumb of the more the better. Let's have a look at the other role.

Tar-pitting.
With some luck, the nurglings will not lose a single base by the time they reach hand to hand combat with their target tar-pit unit (a squad of marines, of course). They might have taken a wound or two or one base though. So the question then becomes how many nurgling bases do I need to force a draw with the space marines in close combat?

In close combat, the marines strike first, hitting on 3+, wounding on 3+ and making the wound stick by avoiding 5+ save. For 9 marines, that means 2.67 unsaved wounds -- just about enough to take off a base of nurglings. The power fist sergeant will cause an additional 0.74 wounds, taking the total up to 3.41 wounds.

In exchange, one base of nurglings hits on 4+, wounds on 5+ and makes it stick a third of the time. With 3 attacks per base, (4 on the charge) that comes to 0.167 wounds per base (or 0.33 wounds on the charge). That means I will need at least 18 bases without charging (hahaha) and at least 9 or 10 on the charge.

So the answer to my question is that I will need to take a large (maximized) squad if I want the nurglings to do a half decent tar pitting job. Otherwise, they can simply die fast and provide a screen to my other more valuable troops!

Statistics: How Many Pink Horrors?

Pink horrors are clearly not close combat exponents. They shoot things. Repeatedly. And fast (assault 3). They want to get in range, shoot things and avoid being charged. It's that simple. Add in a little bit of tank hunter, Changeling mischief, and icon bearing and we're done.
Shooting.
So, if they're going to shoot things, then how many horrors do I need to take care of a (say) squad of 5 marines?

Each horror gets 3 shots at BS=3. Hence 1.5 shots will hit. Fifty per cent of that will wound (S4 against T4). That means 0.75 wounds, on average. And then the space marine gets a 3+ armour saving throw. So, 0.25 unsaved wounds per horror.

Hence I need 4 horrors to statistically take care of a single space marine. Therefore a squad of 5 marines need only fear a full pack of 20 pink horrors of Tzeentch. This seems like a very large number realistically. Especially given the points value of the horrors.

Survivability.
Let's have a quick look at their survivability whilst we're here. How many standard shots (i.e. bolter shots fired by a marine ... or BS=4, S=4 shots) can they take?

They'll get hit on 3+, get wounded on 3+ and save on 4+. Hence they stand a 22 per cent probability of being removed from a standard shot. Therefore 4.5 standard shots are required to remove them on average. This means that space marines shooting at them will kill less horrors than horrors will kill marines in a firefight! This is a somewhat surprising result that is often overlooked by marine players. Equally, it is half of the survivability of plaguebearers. Hence I will often take units of 10 or more horrors for my purposes of icon bearing, backed up with a little shooting ability to make eldar (etc.) think twice, before encouraging them to hop along to claim an objective on turn 4 or so.

Further Discussion.
BUT, there is a different reason that I will take horror packs: the Bolt of Tzeentch. A good set up I've found is simply to take a minimum sized squad and equip one horror with the Bolt of Tzeentch for extra anti-tank ability in the daemons army.

And then there's the Changeling. I've discussed this fellow in the past, so I'll simply provide a link to those earlier thoughts.

Statistics: How Many Plaguebearers?

Today, I'll continue my examination of lesser daemon statistics by having a closer look at Nurgle's tallymen: the plaguebearers. They are one of my favourite units in a mixed daemons army list and I don't usually leave home without them.But what do I want my plaguebearers to achieve in a typical mixed daemons army list? Well, they're certainly not there to get their points back through close combat with opposition units. I use them in two primary roles:
(a) Objective securing;
(b) Tar-pitting opposing units (and monstrous creatures).

Before we get in to it, I will also note that I use plaguebearers to hold chaos icons in my mixed army lists given their survivability and have long ago concluded that they're the only lesser daemons that are worth while taking a chaos instrument for. That can also make for some neat wound allocation shenannigans, but I won't get in to that!

Objective Grabbing.
Usually, I will sit a unit of plaguebearers on an objective (if it is an objective game), hunker down and sit there for the entire game. Perhaps some other units might deep strike off their icon to support them; perhaps not. I will usually aim to place an icon in a piece of terrain as well, so they'll get approximately a 4+ cover save.

Let's assume that they get 10 incoming shots per turn. How many plaguebearers do I need for a 5, 6, or 7 turn game so that at least 1 of them survives (statistically)?

We'll assume the shots are from marines (hitting on 3+) and wounding on 5+ (thanks to the daemons high toughness rating). For 10 shots, there are 2.22 wounds resulting.

Their cover save means 1.11 wounds stick and the feel no pain special rule reduces that down even further to 0.55 wounds. Hence over 5 or 6 game turns, there are approximately 3 daemons sent back to the warp. Four in a 7 turn game. Hence I could get away with a minimum sized squad if I believed that they would be mostly left alone apart from a puny 10 bolter rounds per turn!

Tar-pitting.
Let's have a look at the other role I have for them -- tar-pitting other units. What do I mean by tar-pitting? Simply making sure that other units are in close combat with the plaguebearers and not attending to other units that might be better targets for shooting (etc.).

We'll assume that the situation is that I want to tie-up 10 space marines in close combat for most of the game (thereby keeping them away from objectives and preventing them from shooting my more fragile daemonettes or bloodletters). One of the marines is a sergeant with a power fist.

Given that the plaguebearers enter play via deep-strike, we'll assume that they take some incoming firepower from the marines. This will result in approximately 1 plaguebearer heading back to the warp (give or take a little margin of error).

The marines strike first, hitting on 4+ and wounding on 5+ (with 2 attacks each, let's assume). If the plaguebearers charged in, they will take 3.33 wounds, of which 1.11 stick after their saves and feel-no-pain rolls. In return, the plaguebearers will hit and wound on 4+ (with re-rolls to wound due to poisoned attacks). For every plaguebearer, that results in 0.25 unsaved wounds on the charge. The sergeant with the power fist will then cause 1.11 wounds of which 0.74 stick. So, the plaguebearers need to number at least 8 strong to get better than even odds of a draw (which my instrument of chaos then means I'll convert in to a won close combat). Add in a few extras to survive the incoming fire, and about 9 or 10 plaguebearers will be needed. This number again feels about right from play experience.

Statistics: How Many Daemonettes?

With daemonettes of Slaanesh, I want them to primarily be rapid moving infantry killers, with a secondary suite in light tank busting. So how many of them do I need to accomplish each of those tasks with a reasonable chance of success?Against Infantry.
We'll use the same situation as with the bloodletters: a ten man strong space marine squad armed with bolters, a multi-melta and a flamer. How many daemonettes might I lose before they reach their target? Well, firstly I'm going to suggest that they can completely avoid the flamer due to their fleet special rule. With luck, they may also be able to avoid rapid fire range of the bolters (depending on the opponent and the gaming situation at hand). Hence, we have 8 bolter shots and a multi-melta shot to weather before close combat ensues. The bolters hit on 3+ and wound on 3+. The multi-melta wounds on 2+. In total, I might expect an average of 3.56 + 0.11 = 3.67 wounds. Each daemonette gets a 5+ invulnerable save, leading to 2.45 unsaved wounds. Let's round that up and say 3 daemonettes may die before getting in to melee with the space marines.

In close combat, the daemonettes strike first due to their high initiative. They have 4 attacks each on the charge, hitting on 4+. Hence 2 attacks will hit on average. Of those hits, one in six will cause a wound and a further one in six will rend (i.e. no save). Therefore the marines take 0.33 "normal" wounds and 0.33 rending wounds, on average. With a 3+ save against the normal wound, the typical daemonette causes 0.44 unsaved wounds on the charge. Even with 20 daemonettes, I'm not going to be able to alpha strike the space marines out of existence. But for a smaller squad of, say 5 marines, 12 daemonettes will take care of them in an alpha strike on average. From experience, this feels about right given that I usually have to back my daemonettes up in close combat with another unit.
Light Tank Busting.
Remarkably, daemonettes can pose a problem to AV=10 tanks. This is due to the rending special rule. If they roll a 6 on their armour penetration, it means they get an extra d3 to roll. That extra d3 results in at least a glancing hit (penetrating two thirds of the time). Assuming that the daemonettes charge the tank, they will get 4 attacks each. Hence even two daemonettes should be statistcally enough to result in a glancing hit if the tank has not moved. Three daemonettes would be needed if they are only hitting on 4+ to cause a glancing hit. At flat out speed, they will be hitting on 6+. To cause a glance (statistically), we will then need 9 daemonettes.

Of course, I haven't spoken about the result of the glance or penetrating hit. That's another die roll entirely. But against tanks that haven't moved, or have only moved a "normal" amount, daemonettes in small numbers can pose problems. Hence I think I will take about 12 daemonettes in a squad: not only is it fluffy, but they can also handle a small combat against marines and pose issues to light tanks.

Statistics: How Many Bloodletters?

This week, I'm going to be writing a series of four articles looking at the troops choices for the four main chaos powers in Codex: Chaos Daemons in a similar way that I looked at the advantages of plague marines and noise marines in the past. Today, we're starting with Bloodletters of Khorne.Not so long ago, Raptor1313 wrote an article on how evaluating units by making their own points cost back is overly simplistic. So, what is it that I want bloodletters in my (mixed daemons) armies to do exactly? I personally think that the answer to that is to do what they do best: kill infantry quickly and efficiently. I'm not bothered if they don't make back their points. I just want to be certain that they do their job.

The situation.
Most commonly, I use bloodletters to take out squads of space marines. So in my considerations below, I will assume that I want my bloodletters to take on a squad of 10 marines. I will assume that one of the marines is a sergeant with a power fist. Perhaps one of the more typical set-ups that I come across is multi-melta plus flamer special weapons in these squads, so I will assume that as well.

In game terms, my bloodletters have to deep strike in. I will assume that this goes reasonably well and then I run them to ensure not too many bloodletters get whacked by templates and to get closer to their quarry. The marines will sit still and rapid fire them. After that, I will have my bloodletters assault the marines. (Of course, sometimes the marines may choose to charge them rather than the other way around, so this situation is necessarily simplistic!).

The question is this: how many bloodletters do I need to (statistically) achieve the goal of destroying the opposition (without having to rely upon them fleeing and the bloodletters catching up with them)?

Calculations.
The first step in this calculation is to determine how many wounds are caused by the space marines on the bloodletters before they can get in to combat. That's 8 rapid firing bolters, 1 flamer and 1 multi-melta. I'm going to assume that the flamer template hits 2 bloodletters (which may or may not be accurate in a real game - this is purely a thought experiment!).

How many hits do the bloodletters take on average from this volley? Firstly, there are 16 bolter rounds to consider. Two-thirds of them will hits -- meaning 11 hits (rounded up). We'll add 2 hits from the flamer, which makes for 13 strength 4 hits. I'm simply going to be pessimistic (from my bloodletter's point of view) and assume that the multi-melta also hits them.

How many wounds result from that? Well, half of the strength 4 hits will wound. That means approximately 7 wounds ... and we'll just assume the multi-melta causes a wound as well. So 8 wounds in total.

How many bloodletters survive? Their 5+ save is invulnerable, so they get a save from everything (just not a terribly good one). About 3 of those 8 wounded will survive.

For the win.
To fulfil my wants for the bloodletters, I must take out the entire marine squad in one round of combat. How many are needed?

The bloodletters on the charge have the benefit of the furious charge universal special rule. They're hitting and wounding on 3+. Moreover, they're killing on 3+ thanks to their hellblades. Moreover, they're charging, so they get 3 attacks each. That means 1.33 marines removed per bloodletter. I'd need 7.5 bloodletters to assure myself (statistically) that the marines would be removed entirely. Since they strike first (due to the higher initiative) the marines don't even strike back(!)

How many?
I lose about 5 bloodletters to the rapid firing marines. I need 7.5 to survive in order to wipe them out. Hence 5 + 7.5 = 12.5. Rounding up - this means about 13 bloodletters to achieve my aims. Although I will note that I've been pessimistic along the way (regarding the multi-melta which may not hit or wound, but I assumed it would!). Twelve bloodletters should be fine.

Shortcomings and caveats.
Of course, I've ignored the fact that sweeping advances could work just as well (against chaos marines!). Or if my opponent is near the board edge, they could certainly flee away and off the battlefield. And there could always be faults in my logic above! (let me know!). But overall, and from experience, I know that 10 bloodletters sometimes pulls up short, hence a unit of 12 or so bloodletters feels like it is about the right answer to my original question.