Originally Posted by
CptJesus
With the advent of wrath, Blizzard introduced potion sickness, which allows you to use only 1 potion per combat cycle. However, potion sickness clearly states that the cooldown will begin as soon as you leave combat. If at the beginning of a boss battle, you pop say, a Wild Magic potion, you will have the wild magic buff for the first 15 seconds of the fight. Because you are not in combat when the potion is used, the cooldown begins, and 2 minutes later, you can use another one.
This trick isn't all that useful for most people, but for people who are attempting to maximize their DPS for progression, its a useful little tool and not really common knowledge.