Luckydo Trick

In Kun-lai Summit, on the Burlap Trail (That is between Kota Basecamp at 43,70 and One Keg at 57,62) there are lots of monkey camps. Within these camps are clickable items that grant short duration buffs, called Luckydos. There are three types, but only one is important; the jar shaped one. The buff it provides is "Increases critical damage by 200% and critical chance by 100% for the next 5 charges or 20 seconds."

Now the thing is, with this buff you can snapshot a lot of spells to be 100% critical strike chance, but I noticed while on my mage that certain spells do not use up any of the 5 charges. Nether Tempest is one example, I put it on the entire camp and watched them get destroyed. I tested it on my priest and Shadow Word: Pain had the same effect. 

So this may be of help for leveling or farming, or if you just happen to stumble across the Luckydo.

The following spells work for this:

• Agony, Corruption, Rain of Fire, Malefic Grasp. (Havent tried demo)
• Shadow Word: Pain (Divine Star did not, neither did holy fire)
• Nether Tempest

Based on this I would assume Living Bomb and blizzard would also work.