Yeah Arch is correct.
I know what you are thinking though.
Chance to succede once on 1 dice is 66.66% surely that increases if you try twice? Thing is though that you will fail to successfully cast once, because you have successfully cast twice. See what I mean? So the second dice reduces your chance to succede once because of the extra chance to succede twice. Remember the total probability has to add up to 1 (100%).
Now back to the main thread:
With two dice, and casting with one dice at 3+
2 Success 43.5%
1 Success 45.6%
0 Success 10.9%
casting with two dice 3+
IF 2.7%
1 Success 94.4%
Miscast 2.7%
If we look here we can see that if you roll 2 dice you have a 94.4% chance of succeding once. Compared to only 89.1% of succeding
AT LEAST once with two dice, which includes a 43.5% chance of succeding twice. Those percentages are very close only 5.3% in it (little more than 1/20).
However, the two dice senario has 2.7% chance of misfiring or IFing (5.4%). The miscast is very very bad, especially if it happens to your general. By comparison how much is the IF worth to you? I would suggest not much, a guarenteed d6 skellies big whoop. d6 skellies are worth what compared to your general? Also an IF fails to draw out any DD or scrolls from your opponent. So you could in fact argue that in the case of IoN an IF result would actually be a negitive result. I mean the main question in this thread is how many DD am I sucking out of my opponent right?
Considering this the 2 x 1 dice senario gets a nice boost.
EDIT: I thought I would highlight the fact that the 2x1 senario provides more successful casts, which is very useful. However, that is before any dispelling attempts.
However!
there are other dispelling considerations to make. (forgive me for not using much maths, I would only stuff it up).
firstly the good news for the 2 x 1 dice senario. you have a +1 for each cast, if you are casting twice then you are adding that +1 to two rolls. If you cast once with 2 dice, then you are only adding it once. So theoretically you are getting more bang for your buck out of the skullstaff/bloodpower when you use two single dice.
Now the bad. 1x2 dice is hard to dispell. You are looking at an average roll of 7+1 so your opponent will need an 8 to succede. Most opponents will throw 2 dice at this, and they will fail most of the time. Some will use 3 to be "sure". the best result is 12+1 meaning that 4DD (average 14) will be the order of the day.
A success on 1 dice averages at 3.5+1 so your opponent needs 4-5 to succede and will very likely to succede with two dice. The best result will be 6+1 and again the opponent is more likely to succede than fail with 2 dice. So the only time you are better off with 2 casts of 1 dice is the 43.5% of the time that you succede with both casts.
EDIT: If you roll badly with 2 dice say rolling 3-6 (38.889% chance) then obviously that is comparible to the 1 dice score, however this is comparing bad luck with 2d6 to good luck with 1D6 which is a bit rude lol.
EDIT part 2: [philosophy alert] As a guideline you should consider that (excuse me if this makes no sense) 2D6 is exactly 1D6 more than 1D6. So if you rolled a 5 on the 1D6 roll, then you are essentially comparing that to 1D6+5 for the 2D6 roll. This is true because the choice you make is whether or not you roll the second dice. In each senario you roll the first dice, it's only the second dice that is different. Does that make any sense at all? [/philosophy]
(dodgy maths alert)
94.4% (success rate with two dice) - 43.5% (chances of 2 successes with 2x1 dice) = 50.9% as 50.9 > 43.5 I would suggest that 1x2 dice would be better than 2x1 dice slightly more often.
/dodgy maths
Okay so we have established that an average successful cast with two dice is better than the best possible with 1 success from 1 dice.
How does 1 success with 2 dice compare with 2 successes with 1 dice?
Average result on 2 dice is 7+1 requiring 8 to dispell. with 2 dice your opponent has a 5/12 chance of succeding (41.667%).
Average result on 1 dice is 3.5+1. lets say 1 requires a 4 and the other a 5. if your opponent uses 1 dice twice.
50% chance of beating the 4
33.33% of beating the 5
(16.665% of beating both)
Chances are you are likely to draw out a second DD to beat the 5
50% beat the 4
83.333% beat the 5
Grand total of 41.667% chance to beat them both
So the difference between a 1x2 success and 2x1 successes is (on average) exactly 1 DD
I love it when things work out like that.
EDIT: Another point to consider is that with 1x2 the dispell is either a pass or fail. With 2x1 you might pass both, fail both, pass 1 and fail the other, fail one and pass the other.
But always remember a bad result on 1x2 is your general blowing up (2.7% misfire). A bad result on 2x1 is losing two PD for nothing (10.9%) but trying again next turn...
I hope I managed to both; be correct and make some sense.
