[Max Power]

Hi everyone!

Runes of Witnessing has always been a conflicting choice among Farseer wargear for me. On one hand, it adds greater reliability in the casting of psychic powers but on the other, it increases the chances of our leader's soul being eaten by a daemon, having her brains explode, become the punchline of a T4 psycher's joke, etc. It also makes an already costly, but non-scoring, unit even greater in price. So is it worth it?

To decide once and for all, I did a little Math Hammer to see if the reliability actually did out weigh the risk and cost. This is what I found:

Without RoW, chance of Perils of the Warp killing your psycher = 1.5% and chance of success for the psychic power = 91.7%, per psychic test. Meanwhile, with Row, chance of a Perils of the Warp death = 1.7% and chance of success of the psychic power = 98.1%. So there is a .2% increase in PotW and 6.5% increase in casting success. In the short term this seems like a decent trade-off, but lets look at full game scenarios.

Depending how a Farseer is equipped, she could be casting anywhere from 5 to 12 powers per game. If you multiply the number of castings by the chances above you will find:

wout/RoW w/RoW wout/RoW w/RoW
Powers Insta Gib Insta Gib # Cast # Cast
5 0.077 0.084 4.583 4.907
6 0.093 0.100 5.500 5.889
7 0.108 0.117 6.417 6.870
8 0.123 0.134 7.333 7.852
9 0.139 0.150 8.250 8.833
10 0.154 0.167 9.167 9.815
11 0.170 0.184 10.083 10.796
12 0.185 0.201 11.000 11.778

The first column is the number of powers attempted to be cast throughout the game. In the second and third column, the probability of having a successfully inflicted wound taken on your farseer due to PotW (taking into account Ghost Helm and the wounding of a S6 attack), with or without RoW are listed. The last two columns are the total number successful powers cast.

So even with up to 12 attempted powers cast over the course of the game, the increase of a successful PotW attack is only 1.5%, but you will also only successfully cast on average .78 more powers than if you didn't take RoW. Such a minute difference really leaves the decision to you!

Cheers

[JBunny]

Honestly, out of the games I have played, I have had RoW help me alot more than it hurt me. I also typically use Eldrad instead of a normal farseer. He can actually survive the perils.

[Gabriel_]

Don't forget to take the Ghosthelm into account, which nulifies any Perils of the Warp attack on a roll of 3+. Now I don't exactly know what formula is standard for determing probabilities in Math Hammer, because each dice is independent and therefore has no effect to the outcome of the other dice. I don't really understand it, and I don't think I'd use it even if I did. It is nice however to see what the exact chances of a certain outcome are.

But back onto topic. For me Runes of Witnessing seems unnecessary simply because of the Ghosthelm. Overall the chances of getting PotW seem fairly slim, especially based on your calculations, and since it can be prevented on 3+ I'd rather save those points and maybe add something more to my aspect warriors.

[Max Power]

Originally Posted by Gabriel_

Don't forget to take the Ghosthelm into account, which nulifies any Perils of the Warp attack on a roll of 3+. Now I don't exactly know what formula is standard for determing probabilities in Math Hammer, because each dice is independent and therefore has no effect to the outcome of the other dice. I don't really understand it, and I don't think I'd use it even if I did. It is nice however to see what the exact chances of a certain outcome are.

These calculations were done factoring in Ghost Helm and the 1/6 chance of not being wounded, so they are the probabilities of getting successfully wounded by a PotW attack.

[Gabriel_]

I'm still pretty confused. Just because I didn't suffer a Perils of the Warp attack on turn 1 doesn't mean that the chances are increased on turn 2. If you rolled two sets of two dice the outcome of the first set has no effect on the outcome of the second set.

[TigStripe]

The chances of rolling a PotW outcome are rather low, let alone failing a 3+ save via Ghosthelm. And even if you get a PotW, the power still activates. Fortuning your Farseer could allow a second Ghosthelm save, making the chances of taking a wound even less.

Roll 2d6 one hundred times and see how many 2s and 12s you get.

RoW is something I add to a Seer if I find myself with a few extra points. I'd take Runes of Warding over Witnessing any day of the week.

One relevant question, however, is if you have Runes of Witnessing, and you're up against an enemy that utilizes something like a Runes of Warding (3d6, take the two highest), what happens to your roll on a Psychic test? Do they cancel out? Specifically, Tyranids have special units that force that rule on the entire field, forcing Farseers and Librarians to cry out in terror. So...how does that affect Runes of Witnessing?

[Max Power]

Originally Posted by Gabriel_

I'm still pretty confused. Just because I didn't suffer a Perils of the Warp attack on turn 1 doesn't mean that the chances are increased on turn 2. If you rolled two sets of two dice the outcome of the first set has no effect on the outcome of the second set.

The percentages are based on the number of castings over the course of the game. If you survive one time, the second time doesn't become more perilous, but if you cast twice it is more dangerous than if you cast once.

I also realized that one of my numbers was wrong in my calcations! :
I edited in the new values and the difference between using RoW and not is very small. Sorry about the confusion.

[Guitardian]

I think the Ghost helm works just fine versus PotW, and can't justify spending the points that could be far better used upgrading something else - for such a minute additional chance of success. I have rarely (only once I think in my last 5 battles) failed to use a power and twice been attacked by PotW, where the Ghost Helm saved me. Perhaps I get lucky, but it's not a fear of PotW that influences my decision not to use them, just such a costly upgrade for minimal return.

[Fish Ead]

Originally Posted by TigStripe

One relevant question, however, is if you have Runes of Witnessing, and you're up against an enemy that utilizes something like a Runes of Warding (3d6, take the two highest), what happens to your roll on a Psychic test? Do they cancel out? Specifically, Tyranids have special units that force that rule on the entire field, forcing Farseers and Librarians to cry out in terror. So...how does that affect Runes of Witnessing?

In the name of all that is good and reasonable, please, just assume that they cancel. Otherwise you end up with people trying to claim that they auto-pass their psychic tests :

Sorry if I came off a lil snippy, but this issue is just a lil pet peeve of mine. The one time I actually had to debate why Shadows in the Warp shouldn't actually make a Farseer better at casting his powers was one time too many.

[JBunny]

I completely agree that they should cancel out each other. Otherwise it gets way too confusing.