Prevention of Healing from Multiple Sources - How is it Calculated?

Hey, I was thinking of making a n/r with many skills to deny healing. These are:

Malign Intervention (-20% less healing)
Lingering Curse [elite] (- 1/2 Healing)
Defile Flesh (Recieves 2/3 Healing)
Predatory Season (20% less healing)

Also have an Ally throw in Deep wound (10 or 20%)

My question is, how does the game calculate all of this?

Lets for our example use a Heal Other that heals 100 points.

Would it cut like, 2/3 (66), 50% (33), 20% (26.6), 20% (21.??) 10 or 20% (19.?? or 17.??) = 17-19

Or would all the detractions from the 100 stack:

2/3 (-33), 50% (-50), 20% (-20), 20% (-20), 10 or 20% (-10 or 20) = -143 - -133

Or would just the highest count:
50% (-50) = 50.

I extremely doubt the second one cuz that would nerf the concept of healing, so its down to numbers 1 & 3. Can anyone shed some light? Or just go test this? (im too lazy)

My guess would be the first one...Makes more sense to me, perhaps someone else has an opinion?

Well now that I have finally gathered the energy to test it, I will post my results momentarily.

It works like option 2, except:

There's a cap on how high any negative problems can stack. The value for this one is not one I know from memory, but I'm guessing it is either 33% or 50%.

It's important to note that this is the cap for *stacking* these things. In some cases (like movement speed), a single skill will be able to go beyond this limit.

Ok ill keep that in mind, thank you.