3. The 5th Column caves, damn Valkyries would show up just when you didnt' need them to, and sometimes in the walls shooting at you but you couldn't fight back.
This is a problem throughout CoH's life, apparently.
No matter how much patching they did, right up until the end there were maps where enemies would spawn in the walls. Sometimes, they'd spawn close enough to attack the player, but would be impossible to retaliate against.
I've found wall-spawned enemies in CoT Oranbega maps, layer-cake caves, Council/5th column cave-bases, Arachnos bases, and even one instance in a warehouse mish. Generally, the more cramped, organic, and unorthodox the map, the more likely it would be that enemies would wind up spawned in unreachable or untargetable locations.
Now you reminded me of my first encounter with a CoH GM, way back in I8-I9. I'd been running a Council base mish in Striga with a friend of mine, and we had to clear the map of enemies. Unfortunately, we'd gotten down to the last lousy enemy, but it was spawned outside the map. We contacted the GMs in-game and waited. Eventually, about thirty minutes later, a GM showed up and started messaging me. I explained the situation, and the GM checked into it. The GM was invisible this whole time, but he revealed himself just before the resolution.
He appeared as a tsoo eagle enforcer, spread-eagled in the air with no animations. He asked us if we were ready, and then warped the enemy to his location. It was a Zenith hoverbot, and it lasted maybe two thirds of a second once it was attackable. We thanked the GM for the prompt service and went on our way.
To this day, this is still the fastest and most thorough GM response I've ever had on a professionally-run MMO.
