Just how does fizzle work and is calculated?

So I was looking at some skills last night to see how much fizzle I would have if I wanted to wear plate and saw something that struck me as odd so tried to dig deeper. My setup was basically put plate armor on myself until the skill I was examining had some fizzle chance then swap cloth legs for some leather 4% fizzle chance legs and see the change in the skills fizzle. What I found was odd. Some skills I noted what I used and other I just looked at tiers. (and higher tiers often untrained)

In Fire 2nd-4th tiers a 4% item made my actual fizzle chance change by 5 (a 1.25x modifier). But 5th tier 4%=4% change for a 1x modifier.

In Earth:
2nd tier buff at skill 27; a 4% item gave 3% change for 0.75x modifer
2nd tier obsidion arrow at skill 23; 4% item gave 3.2% change for 0.8x modifier
2nd tier root skill at 3; 4% item gave only 2% change for a 0.5x modifer
3rd tier untrained earthquake; 4% item gave 2% change for 0.5x modifier
4th tier was same at 0.5x modifer

All light was the same across the tiers at 0.8x modifer

Death stunk with 2nd and 3rd tier having a 1.35x modifer (4% item gave 5.4% change)
4th and 5th tiers were 1.25x modifier

Water was 0.8x modifer on first tier.

I should mention I have just started doing mage skills so I don't really have any passives or attunements. Think fire is at 9 and earth at 12 for attunements. Pretty much 1 or 0 for rest. It was odd that even different skills in the same tier (for earth at least) had different modifiers and it did not really suggest a higher skill level changed the modifier since my least trained one (root with skill 3) had a better modifier then my arrow at skill 23.

Any clue? Does every glyph basically have its own fizzle modifier? So instead of just adding up chances on armor I now have to go glyph by glyph to see?

 

Yes.

 

Fire has higher negatives (for use by purer magi)

Earth is more 'armour friendly' due to being strength/mitigation based.

Hadn't tested my main, Death. Tier 4 is strong and certainly prone to big fizzle.

I have noticed that +glyph level decreases fizzle at small regular intervals. Don't think attune does anything but +- dmg (by comparison of caster/target values)

 

Some skill trees are more forgiving than others. Sun, Earth and Light seem to be the most forgiving, but in full plate you won't have 0% fizzle past the first or second tier even in those trees.

I have a related question, does increasing a skill also decrease fizzle chance? Does a skill with 50 points in it have a lower chance to fizzle than that same skill with 100 points?

 

I noticed that while leveling. Didn't take proper notes, but it was like 2% decreases every 10 levels or so.

(could be less, and only triggered with new glyph qty... But I'm sure it was more often than that)

 

Yup.

You must mean: Does a skill with 50 points in it have a higher chance to fizzle than that same skill with 100 points?
Answer: yup!