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Spell casting Formula

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Can anyone tell me the spell casting success formula?

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This is a great resource for looking at channelling simulation:

I'll briefly run through my understanding of the maths if you are interested as of wurm unlimited (subject to change)

It is a standard skill check with a difficulty on channelling, with an additional fail chance due to armor limit if wearing heavy armor.

A skill check is a gaussian random using 3 key parameters: skill level, difficulty and bonus.


For spells
Skill level is channelling skill
Difficulty is listed in the spell list

The bonus is (alignment - 49 + deed bonus)*(1+armor bonus) + (Altar Bonus + faith bonus from 90+ faith) + religion check with 0 bonus at the same difficulty capped at 70.


The bonus is then added on to your skill using the following formula


Effective skill = skill + (min( skill, (100 - skilll)/2) * bonus / 100) 

See*+70%2F+100)+for+x+%3D+0+to+100 for an idea of what 70 bonus translates to


The random number is then generated as follows
A slide is calculated of (effective skill^3 - difficulty^3) / 50000 + effective skill - difficulty

A width is calculated of 30 - Abs(effective skill - difficulty) / 4


Below I will use Gauss() to denote a standard gaussian random


result = Gauss() * (width + abs(slide) / 6) + slide


cuttoff = Gauss() * (width - abs(slide) / 6) + slide


if the slide is greater than 0 and the resuilt is greater than the cutoff + max(100-slide, 0) it rolls again

or if the slide is less than 0 and the result is less than the cutoff - max(100+slide, 0) it rolls again


if the result is between -100 and 100 it returns the result or it tries again up to 100 times before giving up and giving either -90 to -95 if over failing or  90 to 95 if over succeeding


If the result is greater than 0 it is a success and improves the cast if greater than the existing cast


casts are improved by power + floor((100 - current cast) / 20)


if the result is less than 0 it fails, shattering if less than -1* item ql or if rolls a 1 in 100 chance.

I may have made a couple of mistakes here and apologies if this is too much maths


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HOLY [I won't say the word here]!  I LOVE math (more than I understand it), and this is impressive.  The fact that someone could reverse engineer this amazes me.  Whether it was you or someone else Thank You for sharing!

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