There are currently 41 perks and if we consider those 7 perks (GENERAL PERKS) are the most useful (life drain, luck, etc) we have:
- 2,4% to find the perk you desire;
- 17% to find one of the general perks;
- 83% to find troops perks (+ hp and +damage) or spells perks (+damage).
However because of exist more troops perks hp and damage: 12 that add health + 12 that add damage= 24 “troops perks”; then we have 10 “spells perks” = 34 perks of 41 perks, the chance to find them is very high, also in my opinion they do on purpose to add “troops health perks” to reduce the chance to get the “General Perks”. Or maybe i’m totally wrong so about this calculations…
Btw now on wikia you can see which perks you can find on determinate gears. For example you’ll find Life Drain perk only on weapon and gloves. However it’s 100% so i need also more info to know if you can find more perks on a same gear.