Allow custom monster types
Summary
Currently, NPC monster types are limited to a dropdown selection.
Mixed type monsters exist (i.e., Goblin Bat Mage is Beast & Humanoid).
There are probably more unusual monster types.
Rather than support each of these, it might be a good solution to just add one last option, "Custom", to the dropdown, which then allows free-form text input for a custom type that is used instead of a dropdown value.
Clearing this custom value would bring back the dropdown.
For those unfamiliar, that is what the 5E system does.
It might make sense to do something similiar with the role dropdown ("Wrecker", "Blocker" and such), although I haven't seen any examples of unusual types there yet.