The Ancient Magus' Bride Episode 21: Necessity Has No Law.
Episode 21 of 24 of The Ancient Magus' Bride, aired March 4, 2018, 25 minutes. Available with English subtitles and dub where released.
Episode summary
Elias and Chise attend Mariel’s coven meeting and meet Phyllis, Mariel’s high priestess. Secretly, Elias is given information that could help Chise. Following the meeting, Chise becomes suspicious of Elias' activities.