"I could die for him."
Translation:Mi povus morti por li.
The other options I got were: "Mi ĝuas morti por li" and "Mi povus morti por laboras". I'm not sure which is worse.
I remember learning these sentences a week or two ago. It's really annoying, because English doesn't distinguish tense/mood the same way that Esperanto does.
The eternal-present (povas morti) has the neutral sense "could die sometime."
The conditional (povus morti) has the unreal sense "could maybe die for him (under the right circumstances)." There is a strong subtext of "but fortunately it seems that I won't have to" - it expects a "se" or "sed."
And when English would use "I can die for him" - as if I were volunteering - that would be the volitional (povu morti).
(To round out the other two forms "mi povis morti" strongly implies "and I did," "povos morti" implies "and I will.")
Just remember that the -as form is more neutral here, and that "could die" is more neutral in English. Deep breaths, this is a language-learning exercise, not a translation-craft exercise.
"Mi mortigus" is "I would kill.
"por lin" is incorrect. It needs to be "por li."
Povas means "can". Povus means "could."