http://wiki.guildwars2.com/wiki/Karma
This should clear up karma boost related questions. Everything stacks except the bonfire with the 50% booster combo or combinations of guild banners with other guild banners (make sure you use one that gives +10%, not +5%).
Maximum effective karma boost is 95%. I verified this a month ago myself, no one has yet to present evidence to the contrary since the patch.
In OP’s video he only used a 5% karma banner, a 50% karma booster and a 15% guild bonus for a total of 70% extra karma. What’s important to understand here is that each little karma boost helps exponentially when dealing with jewelry boxes. The simple way to explain this is if you get more boxes, which give you a higher yield in karma back, which allows you to buy more boxes…etc. Mathematically you can model the box yield as a summation equation where
total boxes opened= ((karma_modifier*avg_karma_return)^0 + (karma_modifier*avg_karma_return)^1 + (karma_modifier*avg_karma_return)^2 + (karma_modifier*avg_karma_return)^3…etc)*starting_karma/4500
4500, to clarify, is the cost of a box.
This can be simplified to Starting_karma/4500 * (1/(1-(karma_modifier*avg_karma_return))
When testing this out make sure that avg_karma_return is less than 1 (the tested value seems to be about .38) and that karma_modifier is expressed as 1.95, or 1.7 in the case of a 95% or 70% boost respectively.
With a .38 average karma return and a 95% boost one could expect to open 3.8 times the number of original boxes. However with only a 70% one only receives 2.8 times the number of boxes originally purchased.
In other words, if you start out with 1 million karma, you could be buying 3.8 million karma worth of boxes instead of 2.8 and that doesn’t even calculate that if you had a larger boost you would have had a higher starting karma in the first place.
TL;DR: Use ice cream, a 10% guild banner karma boost instead of 5%, and a karmic infusion in addition to the boosts you already used for about 36% more profit.
EDIT: avg_karma_return is actually the ratio of the price of a box to the actual average karma returned. I wrote this early in the morning when I couldn’t sleep so please excuse me.
