From a game mechanics sense, this means the end of Investigate from the first set, as the mystery is solved, and the addition of several new mechanics Emerge, Meld, and Escalate to represent things going from bad to worse
It's a Goblin, so you can jam it into Krenko, Mob Boss / Grenzo, Havoc Raiser Goblin Tribal, or a dedicated Sacrifice deck like Sek'Kuar, Deathkeeper
Invasion of Xerex // Vertex Paladin Flip rating: Maybe don't use at all
Smudging: Smudging is usually a minor misprint where the ink that has been laid down on the card gets a little smeared
Graded Population Report: Dark Dragonite [Reverse Holo] #5 Visualize the distrbution of grades in the chart
It say plenty of play in its Standard format, Pioneer, and elsewhere