An incarnation of Laserbeak, and condor/cyborgs for the Cosmic Era
Do not meddle in the affairs of wizards... -- Gildor, via J R R Tolkien
The first sign of the Army of the Lost are the legs. Blown off legs, hopping along wearing their military boots. And not long afterwards, the rest of the Army arrives, and the horizon from left to right is filled with the decomposing bodies, many of which carry weapons. Unless you can outrun them or fortify your position, you will soon be joining this army of the Undead.
A floating city hovers over the capital, seemingly appearing out of nowhere. Its spires are blinking in the morning sun, revealing alien architecture. What will happen next? Rumours spread like wildfire that this is the ancient city that once stood at this very spot. Mystics proclaim that it will take root here once again, crushing the capital under it. Somebody needs to get up there and investigate.