YOU SAID:
Spare him his life from this monstrocity
INTO JAPANESE
この怪獣から彼の人生を惜しまない
BACK INTO ENGLISH
I spare his life from this monster
INTO JAPANESE
私はこの怪物から命を惜しまない
BACK INTO ENGLISH
I spare my life from this monster
INTO JAPANESE
私はこの怪物から私の人生を惜しまない
BACK INTO ENGLISH
I spare my life from this monster
That didn't even make that much sense in English.