Wednesday, April 6, 2011

Do Grey Knights Need Melta?

Self advertisement: If you enjoy this article you will likely enjoy some of my other articles which cover some fundamentals of probabilities.

New Codex time! Can you hear it? That excited buzz, thrumming through the internets?

Yes, I'm a bit late to the party, as per usual. I don't like to be at the head of the pack when it comes to discussing a new codex. I generally start talking about them after they've been available for a while and I've had some time to give it some thought.

There are plenty of other places that provide "bleeding edge" reviews and army lists. Venture forth at your own risk - information quality may vary.

Best not to speak and be thought a fool than let slip tongue and remove all doubt, yes? I'll keep my musings to my local forums for now as I parse through the new Dex...

Anyways, for those of you who are eager to hear more about Nids, rest assured there is more coming. I would like to take a good hard look at the Adepticon results - specifically at Jay Woodcock's excellent showing - and have a good discussion about what this means for us.

But that's for later.

So, Grey Knights.

Long have their players labored in obscurity, hoping and praying for the day of their ascendance. Is that day upon us? At the very least, they are much better off than they were before, lol.

For those of you who don't know, a mixed Grey Knights/Sisters force was my first full 40k army. I had a few hundred points of Necrons from when I was a teen, but when I started playing "for real" as a young adult it was with fire, brimstone and psycannons ablazin'.

Yeah, Grey Knights are a rough army to get into this game with.  In addition to a horrible army, I sucked pretty bad too, which didn't help.

There were some pretty bad ass whoopin's for good ol' Purgatus back in the day.

So I know a bit about what the Grey Knights USED to be like. Now, they are... very different. Let's talk about one of the big changes to their codex: the Psycannon.

Grey Knights used to struggle something righteous to open up anything heavier than Rhinos. "Pure" Grey Knight forces (god bless those poor masochistic bastards) made do with Lascannons on Land Raiders or Dreadnoughts. You know you are scraping the barrel when you bring Godhammer Land Raiders to kill other Land Raiders, lol.

Now, the Psycannon has been reworked, Black Templar style. Why do I say that? Well, the Tank-Hunting-Assault-Cannon-spamming Terminator horde was once something that only the Black Templar could do (and it's an army that I always thought was pretty neat-o, personally). Now Grey Knights can do it too.

A lot of people don't seem to "get" just how important going from Strength 6 to Strength 7 on a rending weapon really is.

It's a huge deal.

Let me just point out that that one point of strength DOUBLES your chances to penetrate a Land Raider.


It also helps with anything below, ya know, AV 12, which could give a crap less about your ability to rend on a 6. "Great, thanks genius, you REALLY penned me on that roll. Double penetration!" (Heh, here come the jokes...)


So the Psycannon is now a general purpose weapon. A jack-of-all-trades. We can tell just by looking at the stat-line that it's capable of killing any vehicle in the game. But how good is it at doing so, exactly?

To go further we will need some maths.

Let me restate here my general philosophy on math-hammer. Math can help to inform decisions, it cannot make decisions.

Some people argue that math-hammer doesn't show you "real world" values, and so should be ignored. Others are so sure that their calculations will hold up on the table that they are shocked when they don't roll average. Neither of these groups understands statistics.

Statistics ALWAYS tell the truth. Sometimes they just aren't saying what you THINK they are saying.

People focus so much on the average that they forget that there are deviations around the average. Did you really think your bolter shot would kill literally one sixth of a Marine every time you fired it?


So the question arises, do the new Grey Knights NEED meltaguns for heavy armor busting? Let's explore that.

Here's a pretty chart for your viewing pleasure:

A bit of explanation: this graph shows the cumulative chance of scoring a destroyed result (either wrecked or exploded) against vehicles of various armor values, with a given number of shots fired from a Psycannon. I put the numbers of shots in increments of 2's because, well, the Psycannon fires in increments of 2's (2 shots when moving, 4 shots when stationary).

This should allow you to determine, for example, that if you have 4 Psycannon units moving, all firing at a Land Raider (so that's 8 shots total), your chances to get at least one destroyed result are about 18%. This doesn't take into account glancing hits against open topped vehicles or any of that crap. Nor does it reflect any of the OTHER effects you might achieve (shaken, stunned, weapon destroyed, immobilized).

It's just a simple probability of destroying the target.

Cover obviously cuts these odds significantly.

Note that all of these lines asymptote towards, but never reach, 100%. There are no 100% chances when you roll dice, no matter how many dice you roll.

So we see that the Psycannon is indeed a reasonable weapon at destroying armor of any type. But perhaps these numbers, without context, are not as meaningful as they could be?

Let us compare this weapon against the fabled meltagun, the gold standard of Land Raider busting.

Clearly, the meltagun has the advantage. Be sure you read the chart properly though, it is quite difficult to throw 24 meltagun shots at a target, while it is a relatively easy manner to accomplish this feat with Psycannons. So we are probably comparing, say, three meltagun shots versus like 16 Psycannon shots. Or whatever. 
It's your army, you figure it out (please keep in mind this is for BS 4 meltaguns... I guess I should have done that with BS 3 Meltaguns as that's largely what Grey Knights actually have access to, but it's late and I'm still sick so be happy).
Note that a large portion of the meltagun's prowess is due to the AP 1 bonus. Perhaps in 6th Rending will grant AP 1, then the Psycannon will TRULY be king... (yeah probably not). 

Now that we have some maths, we need to think about how to properly use them. Psycannons have a relatively short range, but meltaguns have an even shorter one. Meltaguns are like a hammer blow applied once to a hard target to smash it, whereas Psycannons are more like a high pressure water cannon slowly eroding away the target.
Psycannons are likely to have more than one chance at killing their target, whereas meltaguns are generally "one shot, two kills" (first the enemy vehicle dies, then the meltagun unit dies ;). Also, meltaguns are often carried by small, dedicated specialist units focused on tank hunting which allow the rest of your army to engage other targets, whereas the psycannons may require the weight of fire of every unit in your force (perhaps even over several turns) to take down two AV 14 vehicles. 
Again, that's talking about averages. You could always nuke his raider on the first Psycannon shot - like I've had people do to my Land Raiders with Assault Cannons on several occasions - or you may bounce Psycannon bolts off his Crusaders all game long with no effect.

So, do Grey Knights need melta? Well, if by need I mean do they require it to have a decent chance of killing Land Raiders, then the answer is no. But they certainly may want melta, depending upon their particular army list. Maybe they want to be able to throw just ONE unit at a Land Raider to reliably stop it instead of their entire army. Might be a nice option. ;D

Just a few things to ponder as you move forward. Hope you enjoyed, those graphs were a bitch to create (these things always take way more time than I think they will to write).

Until next time...