Take just shy of 30 Apostles, drop in a Razaketh, the Foulblooded, a toolbox of demons like Lord of the Void, Archfiend of Depravity, and other cards that sound like Slayer albums from the 80s, and go to town
However, Bazaar Trader can also be used to target yourself
From a competitive standpoint, Whispers in the Well added a ton of competition-ready cards and shook up the meta nicely following Fabled's laying the foundations and bringing in new waves of players.
They then split up the possible inclusions into three tiers - what Verhey described as the "gotta have: primary elements and most popular characters, followed by the second tier, which is where cool side characters came into play, while the third tier were the deep cuts, like Guy speaking beaver
There is at least a year between vision handoff and the "pencils down" moment
The unique Necron flavor makes even formerly benign artifacts such as Caged Sun feel quite sinister and I think that Warhammer 40,000 fans will see that a lot of thought went into the reflavoring behind these reprints