[2.1] Taiwan NO.1 Windripper Build! 491K Burning Arrow - Uber Atziri clear

Hey man nice build,
just want to know something , under the gem tab on your TS there's (SP) may i know whats SP

May I ask something, I don't get how does this build perform so well that it's even called NO.1 in Taiwan, while it has so weak defense? 8k evasion is kinda low. Is 5k HP + Arrow Dancing + Acrobatics sufficient for end game? Also, I wonder how do you manage mana, as you have no mana leech/regen at all.