This build is op in its own ways, having the early mana increase helps when jungling and can help decide if you need blue buff or not. The Frozen Heart and Spirit Visage helps with cooldown, and also keeps you from being too squishy when taking on enemy champions. Boots of swiftness helps with narrow escapes from enemies with multiple slows, while Sated Devourer and Muramana is your main source of damage late game. Most people wouldn't take teleport just becasue they don't want to get caught out by an enemy shaco, the teleport is there for teleport ganks down bot or up top, or even for split push.