In the Gamers Dissent video, David said that a round is about 6 seconds long, and said that some spells will indeed take more than one round to cast, so you start casting in one round, but can't do anything else.

If the "retreat to the Homestead at the end of time" thing acts like that it could work - it's a special skill that only works if the "flee" flag is active OR it takes two full rounds to activate, or a combination of both.