The Giving Tree

-1 for maxing Nature's Guise and no Soul Ring.

I'd say this is a good guide, except for what JeepLV said. I'd go with Leech Seed to heal without Tangos and to help push enemy heroes off the lane. Except if you pair with another melee (e.g. Tidehunter) then the living armor first is pretty useful to get first. I never take invisibility except for stealth auto-healing, and I'd go for stats before maxing the stealth ability.

Also blink dagger is probably questionable as a core item for a party healer, although it helps make you an initiator of team-fights.

As a kind of tank-healer (Paladin?) this is a good build for supporting an organized, team-fight/lane-push, especially against towers. Aura buff the party, survive, nuke an enemy hero with your ultimate and Leech-seed (punch the hero in the face too), and back off to the rear of the party when at half health (without fleeing).

Yeah.. you never max out invisibility on treant first. It's either leach seed for pushing and ganking or living armor because bonus regen and armor is very strong early. Usually you get only 1 point in Natures Guise.