So acid flask has a 100% chance to apply [Shred Armour] to enemies
There is a node called tempered flask that have 4 slots for points saying * Armor Shred Chance: +100% per point
So if you are shredding armor 100% of the time already, what is the point of this node?
As you put more points in the node, what you’re doing is increasing the ability to shred enemy Armor in greater amounts. 4 points means a 400% Armor Shred chance, so it’ll shred 4 stacks at a time (not including other assistance). Edit - Should be 5 times, sorry: one for Acid Flask’s regular 100% chance, 4 more from the node.
This applies to more-or-less everything that can have a higher than “100%” to proc something. Partial amounts can still occur, too: Poison Chance is 150%? It means you’ll always apply Poison at least once, with a 50% chance for 2 stacks of Poison.