Grasp on Maokai allows you to take aggressive trades during the laning phase thanks to the extra bit on healing combined with your passive heal.
WhyFont of Life
All of Maokai's abilities proc Font of Life to grant a lot of teamfight healing for every member of your team.
WhyConditioning
Conditioning's bonus Armor and Magic Resist synergizes and scales well with the bonus resists from Aftershock, allowing you to survive massive amount of damage.
WhyRevitalize
Revitalize empower's Maokai's passive and Font of Life healing for incredibly strong drawn-out team fights.
WhyBiscuit Delivery
Biscuit Delivery grants you an insane amount of lane sustain allowing you to trade aggressively often when also paired with your passive heal.
WhyCosmic Insight
Cosmic Insight's general CDR utility can pay off in huge teamfights where you are able to keep a target locked down with an extra cast of [W].