Advice: You don't have to use it immediately when it comes off cooldown. Use it in situations in which you will be able to be a turret. You can afford to keep it on CD for a few seconds while you have to move. It is rare that you will miss using the relic an additional time, because you waited a few seconds before using it. Being a great DPS is about knowing the rhythm of the fights and knowing when the best time to use your cooldowns.
The "easiest" fight is against FB (and SC). During that fight, this relic gives you a REALLY good boost.