As been written and explained in PvP section there is a major bolster bug. I will post these clear findings in the Bug Report section in the hope BW will take a look at this, because it could be a major problem when season 4 starts.
All credits go to 'Texoc' who tested this.
Link to original thread: http://www.swtor.com/community/showthread.php?t=785388
As you probably have already noticed, there is some randomness when it comes to lvl60 bolster. Some! players get randomly bolstered and get an additional +3.5k-4k hp and 30-100 more bonus dmg out of nowhere with max expertise/ full pvp gear.
Here is what we tested so far:
Sin (A) and Sin (B) both naked!! (this is very important, no gear, no spec, no stim, only class buffs, same legacy perks + all companion buffs) had identical stats in Willpower, Strength and Endurance on the fleet. In the Warzone, Sin (A) completely naked, had roughly 30k hp, the same he had on the fleet, while Sin (B) had 34k hp. So Sin (B) got additional 4k hp through some magical random bolster bug.
Conclusion:
(1) gear and/or augments have no Impact on the "3.5k+ hp" bolster bug as both sins where naked
This lead us to believe ----> different datachrons might get bolstered
Next Step:
(1) Both Sins compared all codex entries.
(2) Sin (A) spend a few hours and got all datachrons that Sin (B) had
----> Both Sins with the same stats across the board and identical Datachrons
(3) Both joined a WZ again naked, Sin (A) had around 4k hp less than Sin (B)
Conclusion:
(1) character Sin(B) itself is bugged/broken
(2) Sin (A) is missing something that Sin (B) has, perhaps an achievement
Something that attracted our attention:
All chars in our guild, that have this bolster bug are old chars and/or transferred ones. All Chars that are missing the extra bolster thingy are realtively new chars ( most of them actually leveled up with the 12xXP) and are not transferred chars.
So we made a list and asked most PvPers we knew off that have the bolster bug.
Conclusion:
(1) char transfer has probably no impact on the bolster bug ( multiple bugged chars/players could disprove our theory)
(2) All Chars that have this bug are pretty old chars/mains (we asked arround 15 players) - they "youngest" beeing 1 year old, most of the asked players have their bugged char since almost pre 2.0, some even since release.
This leads to ------> older chars seem to have something (achievement/ titel/ bug) that newer once are missing, that causes the bolster to trigger.
If anyone can disprove any of our findings or theories, feel free to post here.
