Settings -> Field Type "Entries" -> Selectable Entries Condition -> condition type "Descendant of"

[mfell]

It's not possible, to create a condition to get all descendants of certain parent id(s).
I think, it would be very useful to have this selection criteria within the Craft core?

My idea is regarding to this discussion on stackexchange:
https://craftcms.stackexchange.com/questions/41892/field-selectable-entries-condition-get-all-descendants-of-certain-id

My solution in the screenshot is NOT working, but it should clarify, what I'm missing.

Section type "structure"

Settings, field definition (not working, of course)

[sweetroll]

This is something we have been needing in recent projects too. Having descendant/ancestor options would be great or even a field that resolves to an array of selectable IDs would allow the above query to work as well as many other uses cases.