I have 12.43% leech and was testing how it behaves with priest stuff like mastery and Trail of Light and such. First thing worth remembering is that you don’t get any leech from healing yourself, so leech isn’t quite as powerful as you’d hope. Second is that leech doesn’t proc if you’re at full health, so logs won’t show all that overhealing it does. But, to the tests:
Holy Word: Serenity, 12.43% returned as leech.
Renew: 12.43%.
Prayer of Healing: 12.43%.
Echo of Light: 12.43%.
Then…
Flash Heal, 7.5%. What’s going on? Try again: 12.4%. Try again: 9.3%. 12.4%. 11.5%. The amount returned keeps changing without any noticeable logic to it. Tested with and without Trail of Light talent, numbers keep varying. And not once is the leech value higher than expected, always correct or lower.
A bug maybe? Or does it depend on whom I healed (targets were random players/NPCs nearby)? Why would it? To make things weirder, then Echo of Light started behaving random aswell.
Some raw numbers here from combat log:
Your Flash Heal healed xxx 0 Holy. (28,939 Overhealed)
Your Trail of Light healed xxx 0 Holy. (10,128 Overhealed)
Your Leech healed You 4,242 Physical.
Your Echo of Lighthealed xxx 0 Holy (4,781 Overhealed)
Your Echo of Lighthealed xxx 0 Holy (860 Overhealed)
Your Leech healed You 649 Physical.
Your Echo of Lighthealed xxx 0 Holy (4,780 Overhealed)
Your Echo of Lighthealed xxx 0 Holy (860 Overhealed)
Your Leech healed You 648 Physical.
… then few seconds later another cast…
Your Flash Heal healed xxx 0 Holy. (28,939 Overhealed)
Your Trail of Light healed xxx 0 Holy. (10,129 Overhealed)
Your Leech healed You 4,854 Physical.
Your Echo of Lighthealed xxx 0 Holy (4,781 Overhealed)
Your Echo of Lighthealed xxx 0 Holy (1,673 Overhealed)
Your Leech healed You 802 Physical.
Your Echo of Lighthealed xxx 0 Holy (4,780 Overhealed)
Your Echo of Lighthealed xxx 0 Holy (1,673 Overhealed)
Your Leech healed You 802 Physical.
So: two identically sized Flash Heals, totally different Leech and Echo values. The second cast values are correct, first one all wrong. There were no procs present, and even then, procs would increase the numbers, not decrease.
So, mystery.