Wrack Construct not working on Purple Named

[ThePrincipal]

mechanic here. wrack works for one 3-bolt blast and is a 15 second debuff. the repeater has to be loaded and ready to fire. if you hit the wrack button and get the timing wrong, you wont shoot anything but the wrack cooldown still triggers. cooldown is fairly short.

[Puppetian]

Could never get it to apply on any of the purple named mobs, and given the frustrating nature of the thing when used with a repeater it's hardly worth bothering with, as I'm quite sure I'll do more dps if I can focus on something else than keeping an eye on the animation to time the wrack just right.