So as I understand it, these anomalies will occasionally spit out extra-dimensional beasties while they are in the reality bubble, and at present there is no way to close them or use them for any purpose.
With that in mind, how does the game decide how & where to spawn the various nether creatures?
Do they have to appear on the portal tile itself, or can they appear in an area around it?
If monsters can spawn in the area around it, what is the radius of that spawn zone?
Will any construction prevent a tile from being considered for spawning (ex: an open door), or just impassable ones (walls)?
Could I for example, build a wall around a portal, but leave a door on one side adjacent to the portal to act as an “iris” so that nothing can spawn and the portal is inaccessible unless the door is open? Or if the spawning effect is an area, have the entire area filled in with wall sections except for a single corridor of doors.