Looks like some scripts got leaked, not going to look for them myself.
http://www.digitalspy.co.uk/tv/s7/doctor-who/feature/a582838/keepmespoilerfree-why-doctor-who-fans-should-avoid-leaked-scripts.html#~oJswBRhb2k0x3P
Spoiler tag below is of an enemy that is due to return in this series.
Cybermen will return this series http://www.digitalspy.co.uk/tv/s7/doctor-who/news/a581170/peter-capaldi-to-face-the-cybermen-in-doctor-who-series-8.html#~oJsvLFotOupRQm