Fortunately for Eren and unfortunately for the three-person team, Eren had chosen to attack Krista with blunt force.
The blunt force effect was something Rupen was not able to completely mirror as it is. He had to use another spell in conjunction with his default mirror spell to enhance its effects.
Eren had not exerted his full force to crush Krista in his previous attack. And he was glad he didn't. He would have been in a much more dire condition if he had.
Even with his limited interaction, the butcher could decipher the limits of Rupen's spells. His soul sense had helped him know the intentions behind Rupen's attacks as well as read some of his thoughts. With that, he realized that Rupen was waiting for an opportunity that never came to him.
Rupen had a lot of limitations when he could use his spells. Especially because the guy had chosen to remain in the shadows for so long.
