If you forget to start the game with Imperiex's drill terrain markers, are you able to give him a double power action to place them adjacent to him from off the map?

if you forget to place imperiex would you be allowed to have him join the match late?

I was playing a judge at a venue once that forgot one of his pieces but didn't realize it until like 3-4 turns in. He was beating me badly. Anyway, he decided the best place to put the figure is where they would have been had they been in the game the whole time. So he put them out on the map with the rest of his figures. Granted he put them in hindering terrain (and they didn't have any powers or abilities that allowed the to ignore hindering terrain for movement, nor did they have stealth), and they were not adjacent to one of my figures nor did they have a clear LoF to any of them.

It still felt pretty shady. At that point I didn't really care though. My Flash familiy speedsters was getting the snot kicked out of them by Darkseid and his Apokolips army.

If there are no Drill tokens on the map, where would Summon the Hollowers get them?

While you could perhaps make a case for bringing them in from outside the game, I would say if you didn't place the drills, then there are no drills. Wouldn't be the first time a player forgets something like that, but it would probably be the last time they do (or, at least, the last time they forget that particular thing ).

If I'm reading this correctly, the apostrophe implies ownership, which implies that the terrain markers exist in the current game, therefore disabling him from placing them with this power if they were forgotten when the force was revealed.

I can't think of any other clix that create special terrain that could be used to strengthen either side of this dispute.