Guild Wars 2

What exactly is the % “chance when struck” on the Versed in Stone grandmaster trait (Revenant Retribution line: https://wiki.guildwars2.com/wiki/Versed_in_Stone)? With basically any other trait in the game with a “chance on struck” clause, the tooltip tells you what the % chance is. This one does not. Is it a 100% chance to trigger when you drop below 50% health, or some other % chance that’s not stated?
Answer greatly appreciated. Thanks!

When you fall below 50% AND when take damage, it activates. There is no chance, despite saying there is a chance.

Which is weird as why doesn’t it just activate when you fall below 50% health like is beyond me. Meh, bad design is bad.

Nova Stiker.8396:

When you fall below 50% AND when take damage, it activates. There is no chance, despite saying there is a chance.

Which is weird as why doesn’t it just activate when you fall below 50% health like is beyond me. Meh, bad design is bad.

I rather that it activates when it matters like now then to have it activate immediately and get wasted.