24 skills to choose from.
5 runes.
As far as we can tell, you arn't going to want to use a skill without a rune (ther are runes that simply do flat damage increase for example).
You are only going to use the best runes available to you. Saying the exact same build but with one skill that has a lower level rune is a different build is silly.
6 Skill slots.
Assume 20 traits.
3 trait slots.
24 skills to choose from.
5 runes.
As far as we can tell, you arn't going to want to use a skill without a rune (ther are runes that simply do flat damage increase for example).
You are only going to use the best runes available to you. Saying the exact same build but with one skill that has a lower level rune is a different build is silly.
6 Skill slots.
Assume 20 traits.
3 trait slots.
((24*5)*(23*5)*(22*5)*(21*5)*(20*5)*(19*5))*(20*19*18)
(120*115*110*105*100*95)*(6840)
10,357,162,200,000,000
10.3 quadrillion possible builds not including items, per class?
Assuming 15 traits it's
4,133,779,650,000,000 (or 4.1 quadrillion possible builds not including items, per class).
My math might be off (let me know), but I would expect this to be a more likely number.