In the picture example that is shown here, 'Surrounded' is drawn and you resolve the activations from left to right as indicated on the 'Surrounded' card. This is the order in which it takes place (Red then Orange) and doesn't have anything to do with which blip pile is drawn from.

The Red location is the first to spawn in this phase and it will spawn 1 Genestealer because it has a white triangle and on the Void Lock card the white Triangle has a '1' in it showing the number of blip cards that will be drawn. The Orange location will get 1 Genestealer as well.

From page 14 . b. Resolve Genestealer Activations: After resolving the Event Card's ability, each of the boxes on the bottom of the Event card are resolved. The boxes are resolved from left to right and either spawn new Genestealers or move existing swarms of Genestealers.   All this means is that in the pictured example the Red box location gets new Genestealers before the Orange box location. Not which blip pile it's drawn from.

The Ventilator Duct is the 'Red' location on the right side of the formation column, next to Brother Zael and as indicated above, 1 card from the right side blip pile is drawn from and placed on the Ventilator duct.

Next, the Dark Corner is Orange and on the left of the formation column so it gets 1 card from the left side blip pile.

From page 22. Spawning Genestealers are always drawn from the blip pile on the side on which they are being spawned...

The Red location is on the right, so right side blip pile spawns a Genestealer. The Orange location is on the left so the left side blip pile spawns.

Page 23 also shows this in the pictured example shown there.

Amen Cheinzmann.  That is how I play it. Great description.

Nicely done. 

cheinzmann said:

Great explanation! This makes perfect sense to me and a great way to play it.

This, as you explain, makes the priority on the color of terrain. That way if the GS's piles run out the enemy is coming from a particular place first.

The only thing this doesn't explain and I am ready to just set aside as shoddy rules editing, is the wording that indicates putting GS's on the proper side and location of the formation. Why in the world they write that?

TW, the only thing I can tell you about that is that regardless of terrain, GS spawned on the left side of the formation come from the left blip pile, GS spawned on the right side of the formation come from the right blip pile.  The fact that there are two spawns on the bottom of the activation area of the event card, and you simply read them left to right, doesn't have anything to do with the actual location of the spawns.  That is dictated by the color of the terrain.  Some event cards cause both spawns to be on one side of the formation.  Sometimes the a blip pile runs out of GS before the the spawn can be fully populated (in which case traveling occurs at the END that event phase, unless you're at the final location).  But since the activation section of the event card is read left to right, ALL spawns take place before the GS move.

Hope that helps.  :-)

 The Event cards are just randomizers to keep the replay-ability up. It would be very boring to me if I knew playing a solo adventure that 2 Genestealers always spawn here, 1 always spawns there so I have to always move this Marine up, then always pick the guy with the claws, etc. 

TWThomas said:

This is because you could, for example, have a red terrain card on both sides of the formation, or two red terrain cards on a singe side, etc.  The GS spawn on the proper side and location based on the terrain card location with the matching color.

TWThomas said:

But if you can take cards from any blip pile, why would there be 2 separate blip piles, one for each side of the formation? Why wouldn't there just be a single pool, that would be drawn from?