RTB said:
But the odds are pretty bad. You need to roll Cunning, tier 5 staffmods, Lightning Sentry as +skill, 10% for +3. A rough estimate would be 1 in 20,000 if you have a claw that can get staffmods. If you're shopping the odds are even worse.
Cunning chance on a magic item ilvl 90 suwayyah 1/655
Tier 5 chance ilvl 90 = 100%-10%-20%-10% = 60% 6/10
lightning sentry when tier 5 = 1/6
+3 skills 1/10
1/(655*10*6*10) = 1/393000 far worse then your guess, sorry. now given that some fall with 3 staffmods some with 2 and some with none the chances are probably a significant digit better so about 1/39300 or about 1/2 your given percentage.
They are for lack of a better term rare to find/make/buy. but still possible and still more likely then getting a +3 elemental club of fissures, that I have been looking for forever it seems.