I think the Mimic's "spell" is worded incorrectly. It says they have the top hero's top skill and the bottom hero's bottom skill, but it appears to actually be the top hero's bottom skill and the bottom hero's top skill.
I didn't see anything in the almanac or help pages, so how does letting enemies flee work? What are the reasons to say yes or no? I'm guessing letting them flee just helps you end combat a little quicker, but what is the trade-off? Does it slow down the hero upgrades or something if they flee?