Plot problem

By terrafex, in Descent: Journeys in the Dark

Im playing a campaign and chose the ascension plot. i see three other cards in that plot have 0 for the EP value. Can i put them into play when ever i want or dod i just get the one plot i chose in the begining?

Thanks

Age

I'm pretty sure they are conditional on you burning some cities

You have to raze a city for each of them, it says on the card itself.