Killmonger is confusing

I have read his description a million times and I still dont understand him. Can someone explain his reverberation and unstoppable traits to me. I can beat him without using revives for my champs, but I want to one shot him for once.
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Comments
This is how he gains his unstoppable
Should be purple
Speaking of his L2 though, watch out for the last part of it; he stabs his two blades forward, but after a moment, he does a little slash with them. It looks like that forward stab is the end, as it is a similar ending to some other specials, but that little slash is still coming, so don't rush in too soon.