expression, godan verb (-su)
risk one's life; do at the risk of death
Often used in the pattern 死を賭して (risking one's life) to describe a determined action. The verb 賭す is a literary or formal variant of 賭ける.
彼は死を賭してその秘密を守った。
He risked his life to protect that secret.
死を賭す覚悟で戦
He faced the battle with the resolve to risk his life.