tricked into using magic, takes damage from hitting wall

Just as he stretched his fingers out before her, bright red blood suddenly burst from
Accelerator’s right arm.
“…Ah?”
A bullet had not made it past his wall of reflection.
Accelerator could not be harmed even by invisible threats such as gas or a biological
weapon.
This had been caused by a non-external threat.
That is, his body was being destroyed from the inside.
The last remaining attacker jumped to the side and Accelerator was unable to correct his
motion. He slammed into the wall. Blood was splattered on the wall and it did not quite
seem real to him that it was his own.
Still leaning against the wall, Accelerator said, “It…can’t be…”
“One fact remains the same for every esper,” said the woman as she held up her bullpupstyle rifle. “When a scientifically-created esper uses a magical spell, they are assaulted
by a certain side effect.”
“…You’re…a magician…!?”
He tried to shout out but instead coughed up a clump of blood from deep in his throat.
The attackers’ movements. The way they had fled. The timing with which they had been
taken out.
It had all been calculated out to make Accelerator take certain actions—to make him pull
the trigger known as magic.
The specifics of the magic he was made to use did not matter.
It could be something relatively useless like sending a pale light from his fingertips or
even something so trivial it could not be seen. What mattered was that they were making
an esper use magic.
Accelerator managed to figure that much out, but he could also tell his consciousness
was growing muddy.
He had used something like magic in the past, but making careful adjustments while
checking on one’s limits was very different from charging in unaware.

- New Testament Volume 3 Chapter 2 Part 21