Are there any good phrases that I can use, as an alternative to: "Putting his life in danger"?

Answer 1

To put someone's life in danger is:
to periclitate
to endanger him
to imperil him
to jeopardize him
to compromise his safety

Answer 2

Putting his life on the line.
Putting himself in harm's way.
Endangering himself.
Risking his life.
Flirting with death.
Having a death wish.
Not practicing safety.
Being unsafe.
Using dangerous judgment.

Answer 3

Risking his neck