The group Rainbow is referring to is KUTT and we were playing with Engineer ideas last night to better prep for Strategus. In doing so we setup a Forward Spawn in a gatehouse (as Rainbow mentioned) while we were on defense on the first round. We had been getting stuck on Defense most every map up until this round and we decided to build a forward spawn since this particular castle puts you everywhere -except where you want to be.-
We built it on the first round and the only person who managed to place himself to spawn there before the round ended (it literally took the whole round with 2 people doing it) was the only one of us to spawn there when we were moved to offense. For some odd reason, your team failed to recognize him as an enemy, which is understandable, I'd be bewildered as well if there was someone from the other team right next to me when I spawned. He opened the gate, not thinking he was going to get it open, and our team zerg'd in and took the flag. Next round though, he was still the only person that spawned there, your team was better prepared, killed him, and destroyed the spawn.
Long story short..
We'll be more selective of when and where we place these (as we did in maps following that map) because we had every intention of using it safely as a defense position but the autobalance screwed us to offense and made it seem like a griefing tool. In the future we'll wait until the second round (as we did the rest of the night) before building any sort of forward spawn.
Hope that is satisfactory!