From the hunter forums of all places:

This broken mechanic can be found in many other abilities. For example, Lifebloom uses this same ridiculous mechanic. A Druid healer can trinket and temporary buff up, cast Lifebloom on a target, and as long as the Druid keeps the 7 second Lifebloom stack going, each additional stack of Lifebloom will simply multiply the amount of healing the first stack does. Again, this is a stupid mechanic. When the Druid applies the nth stack of Lifebloom after his trinkets wear off, each of the 3 stacks maintains the benefit. With strong enough trinkets, Druids can maintain 3 stacks on 2 different tanks for the entire fight with huge amounts of healing power buffs.

This same mechanic is seen in Earth Shield. It is common practice for Shamans to "pre-buff" Earth Shield. In Arena, many Shamans put on straight +heal gear before the game, pop a Wrath of Air totem, and trinket up, and then apply Earth Shield. Because Earth Shield has 20 stacks, when each stack is burned (when the Shaman is attacked) it is treated as if the Shaman is constantly running that initial level of spelldamage. This is a HUGE exploit.


http://forums.worldofwarcraft.com/thread.html?topicId=1230604208&sid=1

Enjoy!