Ah, actually both. Hotseat and Single player campaign. I assumed the answer applied to both situations, but maybe not.

Is this one of the advances that /needs/ LE or will it trickle down to BB2 without needing to buy the expansion / LE ?

@MrMagic said in [Legendary Edition] Overview Thread:

Ah, actually both. Hotseat and Single player campaign. I assumed the answer applied to both situations, but maybe not.

Is this one of the advances that /needs/ LE or will it trickle down to BB2 without needing to buy the expansion / LE ?

Single player endless campaign is only in the Official Expansion (="Legendary upgrade"). You can find the feature distribution here.