100% more than once. But also vaguely feels like less than 30%.

More than once for Warmaster?  Or Giant Slayer?

The text of Warmaster says 60%, occurs once per skill.  Giant Slayer says 30% chance per each hit of a skill.

The rub is whether Shamael's CA is considered a separate skill instance per CA per debuff placed.

example: Corvis places four poison and one poison sensitivity debuff per opponent.  Shamael either only gets one A1 Warmaster trigger potential, or he gets twenty possible activations, at a 60% chance each attack.

Corvis is taking a lot of damage either way, I just wanna get the most triggers of the mastery, be it Warmaster or Giant Slayer.  Thanks! 😁