Can't beat the onslaught mission (2 augments only)

Been doing this since 8 am (now 1:58 PM) - no success. Everything is pretty easy up until the final 3rd Kayn form, which always results in a loss. I'm so bored of this mode, but I want the icon + gem for the skin bags. What are some tips? I've done malphite with 4 yasuos and specific builds, still nothing. Would anyone mind helping me, either by build recommendations (as malphite or yasuo) or playing?
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