Here's my general thoughts
After Shock has very poor synergy with Sej's passive, 30% extra Armour/MR is completely unneeded with your passive so you shouldn't run it in most cases.
Hextec Flashtraption is pointless because your Q already does its job.
Nullifying Orb needs AD or AP to work, you shouldn't run it on tanks because of that.
Number 3 just makes no sense at all Ultimate Hat and Legend: Tenacity are the only workable masteries here at all.
I'd prefer something like one of these
http://na.leagueoflegends.com/en/featured/preseason-update/8400-8436?build=31020328
http://na.leagueoflegends.com/en/featured/preseason-update/8400-8436?build=31020014
http://na.leagueoflegends.com/en/featured/preseason-update/8400-8436?build=31020138
If you're playing top you could also try
http://na.leagueoflegends.com/en/featured/preseason-update/8400-8437?build=30020216
http://na.leagueoflegends.com/en/featured/preseason-update/8400-8437?build=30020131