I imagine it's probably like a +86 healing, which, as far as I know, gets added to the total that's healed over the entire duration, not per tick.

... if it was per tick, this would be purple.  :-)

I don't know why you have others idols at bank. I got this today and its my 5th idol -- 3rd for resto

as long idols can be changed in combat you can use more of them

and I am using it on macro while I cast rejuv like:
/equip Harold's Rejuvenating Broach
/cast rejuvenation

its gr8, while I have anotherone for lifebloom and healing touch.

efect of the idol keeps on that rejuvenation even you don't have equipped more than only cast that,

next I am using for mangle and RIP.