Guild Wars 2

So I’ve explored Rata Sum extensively as my first character is Asura. I cannot find this guy where is he?

In the room with many purple portals, one of which leads to Lion’s Arch.

north upper level of ratasum. Where in middle you can buy the T1 – T3 gear items.

And if you stay long enough in that middle part you’ll encounter a event between a golem who will sue a Asuran ventor.

Where moto is, you’ll constaly hear “I like to think INSIDE the box!” or “jump in and suprise yourself!”
Also you’ll see billion, kazillion of people standing there.

He is on the left of SAB, north rata Sum, close to the LA asura gate.