Does "X% chance to cast 'Z' when taking damage"

[Taem]

For example: on my armor it says 10% chance to cast level 12 nova, or something like that. Will the nova be a flat level 12, or will it be effected by my masteries in Lighting (since it is level 20 on my sorceress) and pump up the damage a bit?

[Obi2Kenobi]

I have a strong feeling it will effect it, since it effects +elemental damage on items. So a spell certainly should. :)

[Albion Child]

I tested this using a percent to cast level 1 nova armour in act 1 nm on a sorc with level 24 lightning mastery and a barbarian with (obviously) no lightning mastery. As it was only 5% chance to cast, and they (especially the barb) didn't get hit much at that, I didn't have the patience to conduct a "perfect" test, but the bolts seemed to do at least double the damage when used by the sorc.

[Taem]

Thanks for testing that Albion Child. I dont even know how to go about testing that. Well my thought proccess was more based on that jewel and how unfair it could be in duels. Say somehow you managed to find/trade for just two of those jewels. Even if they skill levels didn't stack, its still a substantial amount of damage, combined with masteries??? I see people leveling or even rushing sorceresses to 50 for maxed mastey only, equipting only their jewels of "DOOM", getting a looter and saying, "DUEL ME YOU NOOOOOOBSSS!!!" And of course anyone who duels him will kill him in one hit, but die in the proccess, and he will laugh because he has loot and spent maybe one hour or less rushing his character and he just killed your character you spent days, weeks, or even months on.