LoL Dobby made a video about An Huanhuan and he also uses Conc. I think it's briefly mentioned why in that video. Stack AP to hit with powerful W or smth like that
he needed zhonyas that game. and he needed MR since thalia was main thread. the other 3 items are his core build and boots so he didnt have a slot. im sure when he is really ahead he would buy it tho. just not feasable this game.