So Random Charge Length (RCL) is still something which is causing headaches in this very young 6th edition. It's part of the game now though so like it or hate it, you need to work with it and around it.
So, let's look at some numbers first. At 2", you assault unless you get Overwatched to 2.1", etc. Beyond that you cannot fail which is an improvement on 5th edition through terrain. The max is 12" and that's really unlikely at 1/36" chance but that's double the previous distance maximum for bog-standard units (Beasts/Cavalry are the same but get a movement boost instead). Every inch you get over 6" is infinitely better than the edition before - it's something to think about. Your average with standard deviations and a normal bell curve on a 2D6 set is between 6-8". If you want extreme reliability (approaching 90%) you're sitting at 4" in open terrain. Chuck in terrain and you lose an inch to 3". Chuck in Overwatch and depending what's shooting at you and what's charging, this could add an extra inch or so needed for the charge to be successful. The result is basically if you want to have a high chance of sucessfully assaulting, you need to be within 3-4" of your opponent.
Here are some nice cheat-sheets put together by a forum member - Mypoic Spore.
You can see beyond these ranges (3"-4"), the reliability of getting the charge off drops drastically and this keys into several constructs including Jump Packs, Overwatch & Fleet. However, although charges outside of 4" aren't exactly reliable, they are by no means uncommon, even through terrain. Go flip a coin - how many heads did you flick in six goes? That's how many 7-8" charges in open terrain just succeeded. That's how many 5-6" charges just succeeded through terrain. That's better odds than before through terrain and infinitely better through open terrain. The trade-off? You fail those 6" charges now through open terrain roughly 30% of the time. You also have the chance of failing 3" charges - it ain't likely but it'll happen and there won't be a rock around to trip you up. The fact of the matter is, that although 8" charges are not something to rely upon, they exist. Commonly enough to be a factor.
This has a multitude of effects on being the assaulter and the assaultee.
Prepping the Assault -
Assault units now want to get to that lovely 2" zone. It's going to happen then, even through terrain. It cannot not happen unless Overwatch blitzes the unit. Again, the 3-4" is the comfort zone but 2" is the guaranteed zone. Charges beyond this up to 6" should really be treated like going through terrain in 5th edition - risky at the extremes of 6th edition and with changes of failure even at the lower end. Going through terrain in 6th simply amplifies all of this. You need to prepare for your units to fail charges at 6" then as it will happen often enough. This means protecting the unit from potential return shooting with vehicle hulls if possible. If done correctly, this benefit is two fold.
First, if the charge fails, it's protected from shooting from certain angles next turn. Second, if set up right (and sometimes this is not possible), Overwatch is negligible. You have to see the unit you are charging but not all of it, nor importantly, the closest model. Blocking LoS to part of your unit can also block LoS to part of the unit being charged which means only a handful of their models can overwatch. Hint: block the models which are good at overwatching. This limits the damage they can do and minimises their chances of knocking off your lead models and increasing the charge distance required to succeed. If you block LoS to the lead model through means which he can navigate (i.e. terrain, wrecked vehicle, etc.) that model can still make the initial charge despite not being able to see - as long as the unit could see when the charge was declared.
Remember, this doesn't have to be a blocking where only one member of each unit can see each other but any reduction in Overwatch fire or return fire if the charge fails is better than none. This can even be used on the short-charges just in case they fail. They aren't fool-proof anymore so there are going to be times when your units are left out to dry. This is compensated for by the extended charge range and if you have units which can shrug off most Overwatch firepower (i.e. are tough) or you can limit the Overwatch firepower coming in as discussed above, you can keep trying to get those extended charges in. Particularly if you have Fleet or some sort of re-roll. Pre-measuring is where you can control all of this and ensuring you know the charge probability tables (listed above and below) means you can make the best decisions. Durable units sitting at 7-8" for example are going to love trying for those options unless facing a unit of Fire Dragons for example whilst fragile units like Storm Guardians are going to want to be in that 4" sweet spot before declaring anything, etc.
Charges against vehicles though, well they're like free movement. Still. Only the movement is now more random and larger. And you know what they say about...you know what; It's cinematic. The important part here is vehicles cannot Overwatch - only passengers can from their firepoints (i.e. a limited number). This is great for extra long charges and/or fragile units (though durable/normal units like it, too) as they can really get the benefits of RCL without many of the down-sides. And if they wreck the vehicle, they've got a nice box to hide behind! Be careful of over-extension here though - trading a vehicle for a unit still generally isn't a good trade.
Fleet -
Fleet (which allows you to re-roll any singular or multiple die for charging) is bloody amazing. Let's look at the extracts from that forum post...
Here we can see Fleet is really, bloody, good. Going through terrain with Fleet is better than going through open terrain without Fleet. That's how good it is. You're basically adding 1-2" per category whilst maintaining a similar or even better reliability percentage compared to assaulting normally.
Tying it All Together -
There's a lot of little rules and interactions going on here - and we've only really looked at this from the attacking perspective. In terms of raw rule balance, RCL is interacting with pre-measuring and Overwatch and greatly impacts how a lot of units, USRs and cover mechanics work. The main thing to understand here is that RCL takes some of your control out of the game. Fleet adds some of it back. Again, just imagine you are now always assaulting through cover 5th edition style in terms of what your mindset should be. You can, and need to, work around this. In terms of assault units - they can still work in the black & white sense they did last edition. Throw them at an enemy unit, kill enemy unit and then get shot down next turn. All these rules do is change when that throwing might occur and how much damage the throwing causes them by repeatedly attempting this. The skill involved is going to be making assault unit work without being a big dastardly rock which can accept the shooting after they create a red mist of the opponent or turning into a red mist themselves.
This is where Fleet is really, really awesome, particularly with pre-measuring. First, it let's you get into combat way more reliably and get those extended charges off. We've discussed this. But it gives you more control over how far your unit moves and therefore how it operates in combat (i.e. what parts of the unit are engaged). Say for example there's a unit 6" away. I roll a RCL of 9" with a 5 and a 4 but I want to stay in combat so don't want to be moving that far. I can keep the 5 and re-roll the other die. I get a 1 and thus just make it into combat (remember, Overwatch has already happened at this point so I know EXACTLY what I need thanks to pre-measuring). This flexibility should hopefully highlight the ton of options there are with Fleet in controlling how your unit engages the enemy. Yes, it's great for getting you into assault more reliably and from further away but it importantly brings some of the player control and skill back into the game.
Conclusion -
RCL's biggest change isn't that charges are as random as charging through terrain last edition or that everyone is basically a 5th edition Beast/Cavalry model but the removal of control in how your units engage the opponent. No longer can you move backwards or laterally to set up the perfect charge at 6" through open terrain to pull a unit - RCL makes this too unlikely and thus you need to get closer unless you want to be left out in the open with shooting. This means it's more likely more of your unit will engage and thus limits the effectiveness of assaulting units if they cannot remain in combat. There are still ways around this which will be looked at in a later post but there are still options for this within the RCL mechanic if you have access to re-rolls (i.e. Fleet).
This single USR is almost a requirement for any sort of assaulting unit as it provides the unit with more reliability and gives the controlling player greater control. Overall, charging is probably similar to what we saw in 5th in terms of what actually happens based on averages but the lack of control pushes it down the order in terms of what's good in 6th. Assaults are still good there is no doubt, but consistent skill will generally win out against unreliable rolls. Again, ways around this but the loss of control means the loss of options.
Regardless, hopefully this gives a better understanding of how the RCL mechanic affects assaults and what it means to you as a player with control over movement. It's different but not stupidly broken. And most importantly, It's Cinematic. Keep telling yourself that when you fail a 3" charge ^^.
