With base_entranced we can add additional support for custom classflags, npc flags, entities, etc in siege maps. For example, I have already added a couple of extra .npc file flags that mapmakers can yews:
dempProof 1 = NPC is invulnerable to DEMP damage
specialKnockback 1 = NPC cannot be knockbacked by red team
specialKnockback 2 = NPC cannot be knockbacked by blue team
specialKnockback 3 = NPC cannot be knockbacked by any team
These two flags enable mapmakers to get creative with some "kill-the-NPC" objectives. dempProof will prevent a team from killing the NPC through the wall with demp, and specialKnockback ensures that he won't fly all over the place when getting attacked, or that a particular team can intentionally move the NPC to a desired location.
On a related note, CFL_SINGLE_ROCKET will soon be fixed so you can't get more rocket ammo. This will enable you to yews that classflag properly.
Post any requests for custom mapmaking stuff here.