OK guys, I took the time to sit down and test this...
Procedure: I quickly threw together a little program to help me keep track of things. Upon pressing <SPACE>, the total hits counter would go up. When <ENTER> is pressed, the Guardian activation counter goes up in addition to the total hits counter.
For testing, I used Ludibrium : Terrace Hall (the first Toy Factory map where all the Brown Teddies are).
Testing was as follows:
- Test 1000 hits.
- Misses are ignored.
- Guards from Divine Shield are ignored.
- When Divine Shield activates, I dispel it to continue testing.
- When touch damage occurs, I press <SPACE>.
- When the Guardian animation activates, I press <ENTER>.
- No break was taken during testing.
- No character movement after beginning (other than being knocked around during testing).
- Combat Orders was not used.
Character information:
Level 148 Paladin:
* Level 18 Shield Mastery (18% guard chance)
* Level 13 Guardian (23% block chance)
Results:
Guardian activations: 228
Total hits: 1000
Guard rate: 22.8% (expected 41% - a difference of ~18%)
The guard rate is basically the same as the block chance listed on Guardian. It does not appear to be additive with Shield Mastery's guard chance. Now, is this intended or a glitch? I'm not sure how to go about figuring that out. Hopefully it's the latter, but someone would have to ask Nexon Korea for confirmation, and the only way I can imagine that happening is if enough people report this as a bug so that Nexon America can start the investigation.
Theory: Notice how Shield Mastery says "guard chance" in its description. Then, notice how Guardian says "block chance." Divine Shield is the skill that shows "GUARD" text when hit; perhaps Shield Mastery is actually additive with DS's proc rate? I'm going to test this next.
EDIT: There appears to be no correlation between DS's proc rate and the Shield Mastery guard chance, so
I have filed this as a bug.