Page 1: Casting Spells in 8th Edition|Page 2: Casting Spells in 7th Edition
Casting
What's the optimum number of dice to use when casting a spell in Warhammer 8th edition?
This table shows the chance that you will roll over a certain number depending on how many dice you throw at it and what the optimum number of dice is in each case. To use the table for spell-casting, subtract the wizard level of the caster from the spell's casting value and that's the roll needed to cast.
| Roll Needed (Casting Value - Wizard Level) |
Number of Dice | Optimum Number of Dice |
|||||
| 1 | 2 | 3 | 4 | 5 | 6 | ||
| 3+ | 66.7% | 97.2% | 100.0% | 100.0% | 100.0% | 100.0% | 2 |
| 4+ | 50.0% | 91.7% | 99.5% | 100.0% | 100.0% | 100.0% | 2 |
| 5+ | 33.3% | 83.3% | 98.1% | 99.9% | 100.0% | 100.0% | 3 |
| 6+ | 16.7% | 72.2% | 95.4% | 99.6% | 99.9% | 100.0% | 3 |
| 7+ | 0 | 58.3% | 90.7% | 98.8% | 99.9% | 99.9% | 3 |
| 8+ | 0 | 41.7% | 83.8% | 97.3% | 99.7% | 99.9% | 4 |
| 9+ | 0 | 27.8% | 74.1% | 94.6% | 99.3% | 99.9% | 4 |
| 10+ | 0 | 16.7% | 62.5% | 90.3% | 98.4% | 99.8% | 4 |
| 11+ | 0 | 8.3% | 50.0% | 84.1% | 96.8% | 99.6% | 5 |
| 12+ | 0 | 2.8% | 37.5% | 76.1% | 94.1% | 99.0% | 5 |
| 13+ | 0 | 2.8% | 25.9% | 66.4% | 90.2% | 98.0% | 5 |
| 14+ | 0 | 2.8% | 17.6% | 55.6% | 84.8% | 96.4% | 6 |
| 15+ | 0 | 2.8% | 12.0% | 44.9% | 77.9% | 93.9% | 6 |
| 16+ | 0 | 2.8% | 8.8% | 35.0% | 69.6% | 90.4% | 6 |
| Average Roll | 3.5 | 7.0 | 10.5 | 14.0 | 17.5 | 21.0 | |
| Irresistable Force (and Miscast) |
0 | 2.8% | 7.4% | 13.2% | 19.6% | 26.3% | |
These values include the following condition:
that an irresistable force is a successful cast even if the casting value is not reached.
The table shows that when trying to cast a spell with a low casting value, rolling lots of dice is not a good idea, because there is a greater chance for a miscast.
If your opponent uses the same number of dice to dispel as you used to cast (and uses the same level wizard), he will dispel roughly 60% of your successful casts—for example, if you rolled 2 dice to cast then the average roll you get is 7, and so if he rolls 2 dice to dispel then he has a 58.3% chance to roll 7+ and beat you. So, as a quick rule, multiply the roll needed by 2.5 to see how many times you can expect to get a spell off in a game. 
For example, let's say you have a level 1 wizard with Doom and Darkness (casting value 10) and your opponent also has a level 1 wizard who attempts to dispel with the same number of dice as you cast. You need to roll 9+ to cast. If you attempt to cast it every magic phase, then:
if you use 1 die to cast, you will fail;
if you use 2 dice to cast, you can expect to get the spell off roughly 0.3 x 2.5 = 0.8 times during the game—so don't count on it;
if you use 3 dice to cast, you can expect to get it off roughly 0.7 x 2.5 = 1.8 times; and
if you use the optimal 4 dice, you can expect to get if off roughly 0.9 x 2.5 = 2.3 times.
This approximation does not take into account the effects of irresistable force. The calculator below does take irresistable force into account.
Magic Items: extra dice vs. +1 to cast
Extending the previous example, we now consider the difference between a magic item giving an extra power die and a magic item giving +1 to cast.
We make the assumption that your opponent has as many dispel dice as you have power dice. Then, with an extra power die, you can effectively cast one spell where you use one more dice to cast than your opponent can use to dispel.
If you use 2 dice to cast and he uses 1 to dispel, you can expect to get the spell off 0.8 x 6 = 5.0 times.
If you use 3 and he uses 2, you can expect to get the spell off 0.9 x 5.3 = 4.9 times.
And if you use 4 and he uses 3, you can expect to get the spell off 0.9 x 4.9 = 4.3 times.
With +1 to cast, the multiplier would be 3.5 rather than 2.5.
If you use 1 die to cast, you can expect to get it off 0.5 x 3.5 = 1.8 times.
If you use 2 dice to cast, you can expect to get it off 0.9 x 3.5 = 3.2 times.
And if you use 3 dice to cast, you can expect to get it off 0.9 x 3.5 = 3.2 times.
The values for the extra die are more impressive at a glance, however the chance of a miscast increases with extra dice and it only affects one spell each turn (per extra die). The +1 to cast affects all spells and so the more spells a wizard has, the more desirable it becomes.
Calculator
Here's a little calculator to play with the values:
| Casting value of spell: | |
| Casting bonus: | |
| Number of power dice used: | |
| Opponent's dispelling bonus: | |
| Opponent's dispel dice used: | |
| Number of turns in game: | |
| Expected number of casts: | |
Dispelling
The casting table can also be used for dispelling—for example, if your opponent tries to cast a spell and rolls a total of 6, you should optimally use 3 dice to dispel it.
This page was inspired by Avian's page.
Page 1: Casting Spells in 8th Edition|Page 2: Casting Spells in 7th Edition
Leave a Comment