So it's not often I talk about rules on the blog as I tend to stick to talking about what I'm good at (i.e. not gaming). However, my recent stint with Ravenwing and Deathwing (see here and here) threw up a question in 2 of the games that I couldn't find a simple answer to despite scouring the rulebook and internet. The question, which seems unique to Ravenwing due to jink re-rolls, is can you voluntarily choose a 'worse' save, or perhaps lower is a better term, in order to benefit from a re-roll, thus technically increasing your probability of making the save?
Before I get to the meat of the discussion, let's think about bikes in general. Take generic marine bikers. When you are shot by high AP weaponry in the open, you will choose to use your armour save and thus not compromise shooting next turn by having to fire snap shots. Low AP weapons will almost certainly make you want to jink for that 50:50 chance of a save despite snap shooting next turn. Mixed fire will leave the choice up to you depending how many casualties you anticipate and what you were hoping to shoot next turn. Suffice to say, however, that if you choose to jink, you will use the cover saves for the AP3 and below wounds and the armour saves for everything above. Those are the saves giving you the best chance of surviving - your 'best' save. Whitescars are a little different with skilled rider increasing the jink save to 3+, but the net decision making is the same.
Now lets consider the situation with Ravenwing, who can be subdivided into black knights and bikers. Bikers are very similar to their vanilla counterparts, with the exception of the Ravenwing rule granting a re-roll to jink saves. Correct me if I'm wrong, but a 4+ re-rollable save gives a 75% chance of saving the wound over 66% with a regular armour save. Black knights are somewhat different in that they give skilled rider like with Whitescars, but in conjunction with the Ravenwing rule this makes jinking a very attractive option for them, save for the fact it decreases their plasma talon accuracy and renders their blast grenades useless (which are their greatest assets).
Before I go further with this lets look at some rule definitions. There are 3 directly relevant ones, namely jink, re-rolls and saving throws. Jink is pretty straightforward and the re-rolls section doesn't add much clarification. The saving throws section only really makes one reference of note, in which it refers to the model always being able to use its 'best save' where multiple saves are available. Pretty vague as to what the best save is. I have read arguments claiming that it is the lowest number, as with say a terminator using its 2+ over a 5++, and other arguments stating that the re-roll can't be a consideration for calculating this. Neither the lowest save or greatest probability (considering re-rolls) are therefore definitive answers.
Sadly, there are a few more complicating factors. Darkshrouds hand out the potential for the black knights to gain a 2+ re-rollable jink save. This is obviously open to abuse in a competitive setting. There is also a factor I hadn't considered and that is choosing to decrease your chances of making a save to purposefully kill your own unit, though I'm struggling to find many non-melee situations (which although you would get a cover save you would still have hit and run) in which that would be an issue. And besides, you can always elect not to jink voluntarily so the rules kind of imply that even if your chances of survival were better with a re-rolled cover save, you have the choice not to.
This leads me to where I wrap up. With no clear rulings and much debate between Alex and I, we decided to house rule that you can opt to voluntarily use jink over armour for several reasons. Firstly, we try not to spam lists in our games and so the potential for abuse is limited. Second, given that you sacrifice your offensive potential for defensive gain it seems relatively balanced. Sure, you saved 8.4% more bikes, but they're all snap shooting next turn. Lastly, when trying to extrapolate the 'real world' scenario, the Ravenwing would all elect to jink and wouldn't be particularly selective about what they dodge and what they don't, hence the cover save would be the most applicable. A better way of looking at it maybe is that there are multiple options available and the owning player should simply be able to choose which they prefers to use.
Its the best of an unclear situation and not even necessarily applicable to tournament play, but until the powers that be chip in with a ruling we are at least happy to know where we stand in our games without needing to debate it every time. Please check out the following for further insight into the dilemma and feel free to discuss further. Cheers.
From the Fang