Check it out for yourselves, I get a 1020 heal on killing something. It does seem to have some internal cooldown (10 seconds? needs further testing).
Parasitic bond FIXED?Source
As an FYI: Parasitic Bond now has a 5 second internal cooldown along with its increased healing potential. We’ll put that in the description in the future.
You just need to tag the mob from what I’ve experienced, Lettucemode.
Zoke, we’d like to be able to include things like internal cooldowns within tooltips at some point in the future. 
