Ben 10 (2016) 3x22

Team Tennyson finds out about their British ancestry, so they visit their relative's estate, but mysterious events convince Ben that the place is haunted. However, it turns out that Kevin Levin has followed them to Britain, and showcases three new alien forms based on those Ben has lost: Thornblade (Wildvine), Undertow (Overflow), and Dark Matter (Grey Matter).