Civil War: T’Challa learns that capital punishment is wrong

"T'Challa didn't spare Killmonger. Killmonger died, from wounds T'Challa inflicted on him and then T'Challa refused to save him."

ref·use
/rəˈfyo͞oz/

verb

past tense: refused; past participle: refused

indicate or show that one is not willing to do something.

That part is untrue. He offered to save him, but Killmonger denied it. T'Challa accepted Killmongers wish to die. He didn't refuse him anything as he offered help showing willingness. .