J0N4TH4N - (MRD) added Looming Hoverguard, tested both automatically and manually, works great, and yes, it does move to the top of library just in case you are wondering

projects/mtg/bin/Res/sets/MRD/_cards.dat

@@ -627,6 +627,20 @@ power=10
 toughness=10
 [/card]
 [card]
+text=Flying. When Looming Hoverguard enters the battlefield, put target artifact on top of its owner's library.
+target=artifact
+auto=moveTo(ownerLibrary)
+id=48114
+name=Looming Hoverguard
+rarity=U
+mana={4}{U}{U}
+type=Creature
+subtype=Drone
+power=3
+toughness=3
+abilities=flying
+[/card]
+[card]
 text={W}, {T}: Regenerate target artifact.
 auto={W}{T}:regenerate target(artifact)
 id=46071