It could be interesting to have the same condition as "biome" condition, but for structure (like end city, or bastion etc..)
With that we could create new mob, that only spawn in specifical structure, and I think i'm not the only one who will be interesting in it.
So the suggestion is pretty easy to understand : A new condition, that do the same thing than the biome condition, but for structure.
Thank you ! Titigre