Guild Wars 2

A diverse trait system.
For example, we have three stages of of mastery for every trait line.
(adept, master, grand master)
But what if you want to use 2 adept and a master trait.
(yes i know you can do this already., let me finish)
Since you sacrifice higher tier traits when using lower one, why not have a system that will increase the lower tire traits when used on higher tier slots?
for example, if you have an adept trait that increases damage by 5%, if you use it in a master slot it increases to 7% and grandmaster, 10%.
By doing this players may select traits they would never have used before, and possibly open a new diverse set of builds.

In addition, Anet could make certain traits benefit other traits. say: if you have 2 certain traits selected (not necessarily from the same trait line), then you get a bonus effect. Mix matching traits will open a large number of bonus effects.

Also, they could implement a feature where different class traits will interact with one another to provide special attacks or additional effects, sort of like the preexisting combo finishers.

IDK, it was just a thought i was having…