While above 70% health, gain up to +40 Ability Power or +28 Attack Damage (based on level), Adaptive.
Offense
+1-10% CDR
Flex
+6 Armor
Defense
+15-90 Health
WhyGuardian
Guardian on Rakan allows you to block a large amount of burst damage with a well-timed [E] and the bonus Movement Speed empowers you to follow that up with a strong counter engage.
WhyShield Bash
Shield Bash on Rakan gives you a decent amount of additional defensive power while your passive is on as well as a bit of additional all-in damage pressure.
WhyBone Plating
Bone Plating is great burst damage protection so that you're able to effectively engage and get out with your life.
WhyRevitalize
Revitalize is great at empowering Rakan's heals from items, Font of Life, and [Q] as well as his passive and [E] shielding.
WhyNimbus Cloak
Nimbus Cloak synergizes fantastically with Rakan's [R] granting you the ability to hard engage teamfights easily.
WhyAbsolute Focus
The extra AP from Absolute Focus is great for sustaining in lane with [Q] poke as well as granting you a bit of extra up-front damage with you engage combo.