Question about new Impale Mastery

Hi, I have a question about new Impale Mastery:
20% chance on Hit to remove all Impales from Enemy, Impales removed this way multiply their Reflected Damage for this Hit by the number of Hits they have left

"their Reflected Damage for this Hit" counts as all stored Impale damage for each Impale (because first of all it is said "remove all Impales from Enemy"), that is multiplied after
OR
"their Reflected Damage for this Hit" counts as Impale damage for 1 hit only (as it would work without this Mastery, even though it is said "remove all Impales from Enemy"), that is multiplied after?

I guess it works like in second case (despite the complicated describtion), and this Mastery just gives 20% chance to deal all stored Impaled damage and remove Impales, but why wouldnt GGG increase the chance from 20% then?