Eye of eternity sparks unintended mechanic? (bug?)

So we just did Eye of Eternity... aaaand well, the problem with that is, we actually wanted to use spark stacking for increasing our damage, combining it with heroism, so we rooted all the sparks, gripped them and when we had 5 sparks, we broke them and got 5 buffs, then we used heroism and well... the buff stacking is probably broken or you are not supposed to be able to grip and root sparks so, we got like +660% damage buff, the boss fell to 1 HP before phase 2 and then we just oneshotted the phase 2, survived for phase 3 and then oneshotted the boss, since it was on 1 health. I am not gonna include a screenshot of dps, because of safety issues, but there was a warlock on 50ke in total at the end of th dps (43 million damage fight).

Well, hope this gets fixed.

This is a legit tactic that has been done on icecrown server.

Indeed you're meant to be able to grip/root/stack sparks. However it seems off that you had 660% damage increase from 5 sparks. Should be 50% per spark, so 250%.

Seems like they are stacking multiplicatively

(1,5) ^ 5 = 7,6

Which is a 660% increase