I played about 15 games tonight and could not complete two bounties.
One of them was "Can't Stop" get two kills in one life(two kill streak). The other was "Mine" kill an opponent damaged by another opponent (assist). Both are seriously impossible.
What's the secret how did you finish these?
[spoiler]Is this a bug for you or do they require a specific mode?[/spoiler]
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Note that "Mine" clearly states "damaged by another oponent" - meaning it has to be done in rumble.