ISP:Comcast
Type of Internet Connection: Cable
Internet Connection Speed: 30mbps
Date & Time: Several times over the last few days
Frequency: Alot
Character Name: Dasva
Race: Taru
World: Bahamut
Class/Skill Rank: Run
Area and Coordinates: Abyssea uleguerand range
Party or Solo: Both
NPC Name: None
Monster Name: Worms
In-Game Time:unknown
Steps:
1. Maintained my int the same as the worm holding same worm
2. Let it cast spells on me with with varying amounts vallation merits and 3 runes.
3.
Code:
             no wards     ward no merits      2 merits     4 merits

Stone IV               437             240                    231            222                         
stonega III            498             273                    263            253
quake                  662             364                    350            337
From that you get about 47% to a little over 47% reduction with 2 merits and 3 runes or 49 to a little over 49% with 4 merits. No merits would've been 45%...

So in conclusion while it says it provides an additional point of dmg reduction per rune harbored it seems more like 1% per merit for 3 runes. Not sure if bug or just bad translation but 5/3% reduction per rune fully merited when no merits is 15% seems a weaker than merits usually are