Predecessor Builds > Gideon > Thankfully You are a God
The first thing you want to do with this build is go straight into Tainted Scepter, the reasoning behind this is you want to become relevant as quickly as possible for your carry and support to rotate from mid and help take out their duo, running tainted will help negate their support healing as well as counter any junglers along the way.
Next on the list is Megacosm, this will help you deal some serious damage to your opponents especially to those tanky opponents who can take a hit.
Third in line is Wraith leggings this is another great item to run with because of spectre helping you get the hell away from everybody once you become a bullet sponge from ulting, but it also contains carnage which is great for if you are a few seconds behind in the battle and magically show up if anybody who is sitting below your ult is below 40% health expect them to be dead shortly.
Fourth item is Truesilver bracelet this is a MUST to have near mid / end game gideon because of the fact of the CC Immunity for 4 seconds while casting your ultimate and when trusilver is broken they receive damage of 50% of the opponents strength.
To finalize this great build we couldn't do it any differently than adding Oblivion Crown, Not only do you get Eradicate which increases magical damage by 15% but you also gain oblivion where the next instance of ability damage against an enemy hero will deal another 10% of their current health as magical damage.