You are referring to Willing Vessel as it increases the damage done, but it only increases the healing. Unless i am reading the tooltip wrong.

Edit: So, probably you have no idea what you are talking about, and since half of the guide refers to how you are making the Willing Vessel better, I'd recommend that you keep playing with the hero, in order to first master it and then give a guide. Copying the most popular build from Hotslogs, isn't making a guide.

Also read the tooltips.

Edit 2: Nice job changing the guide.