Chance

We all know that items have a particulary chance that adds some kind of magic thing. But how does it work?

For example, I got a staff with 20% chance on halve casting time of fire spells, and a flame artifact with the 20%.
Do I have 20% + 20% = 40% chance on halve casting time of fire spell then?
Or do I have a 20% chance, when that fails, another 20%?
And what about a reduction, but 2 times? For example, a spell costs 4 sec to cast. You get the 1st 20%, so it only costs you 2 sec, but you get the 2nd 20% too, so it only costs you 1 sec.

Well actually I dun have an idea how it should work. Maybe anyone else does?

There have been a ton of posts on this (mostly by Savio), but in short...

You have a 32% chance of getting 1/2 casting time.
You have a 4% chance of getting 1/4 casting time.

You want have the 40% because you cant wield a Staff and a Artifact at the same time :P

k thnx, but didnt know about the other posts... Srry for that