Ren couldn't protect Leroy because he had to protect his powerless children, and that led to Leroy losing his ability once and for all.
The one who attacked him could destroy someone's ability and make them an ordinary human being.
They could only do this to a solo ability user and after that they had to rest for months to be able to use their special ability to destroy someone else's ability again.
This time, the target was Leroy…
One could see how much the other party hated Leroy until they hired this special assassin to make Leroy suffer.
The assassin was supposed to make Leroy an ordinary human being and then killed him.
Unfortunately, Ren's ice dragon still protected Leroy just before Leroy was killed.
That's how Leroy survived.
If this was the old Leroy, he would be so depressed that he would commit a suicide.