This guide is good, but I have some questions:
1. Why not Exhaust instead of heal? It is great for locking down assassins and bruisers who jump you and your adc, while you already have an effective heal.
2. Show optional items. Not only will this make the build guide more pretty, it will help new learning players.
3. Get Mobility Boots instead of Boots of Swiftness. You need the extra mobility while roaming and placing wards, and during fights you have your passive to move around.