I have a 100% chance for a second attack but it seems to happen pretty randomly. I imagine there’s an internal cooldown or it’d be pretty broken. It doesn’t say what it is though, does anyone know?
As far as my experience goes there is no internal cooldown, or its smth like 0,1 sec or so.
Even my main dps spell (Vengence) that i tested with some of the new passives nodes with between 10%(base) and 40%(all passives nodes) did triggered multiples times in a row.
On another note, i really like this new mastery passive, its no boring stat stick(like raw Attack Speed or Dmg) but some interesting stuff that can work well with alot of spells/skills.