Black Clover Episode 17: Destroyer
Episode 17 of 170 of Black Clover, aired January 30, 2018, 25 minutes. Available with English subtitles and dub where released.
Episode summary
In order to go to the treasure chamber together with his friends, Yuno confronts Mars alongside Klaus, so that the injured Mimosa can heal herself. But they have a hard time harming Mars at all.