The beauty of the build is you don't replace any until super late Spirit items are all improving ult and 1st skill Gun if you need more damage Superior stamina for extra mobility.
You play the supportive healer guy with a decent CC that improves with spirit items. Main goal is to be active a lot especially with ult up but your 1st is decent for ganks. Your 2nd skill is a save and most people don't use it and it reloads both your guns. Its also great in dodging spells like Bebop bombs. Your primary initiation is majestic leap into ult as opposed to warp stone unless needed more mobility.
In this build you won't replace anything until super late or luxury phase to maximize slot efficiency for either the weapon damage, base health, or raw spirit. Most people overlook this part of an item which is tiered per price range.