I think Prognesis is a good choice for a wincon in the proteus staff deck, as it has the same clock as a DSC, without the possibility of being swords'd or having 3+ damage blocked and the opponent racing with their other creatures. IMO plats and Prog should be the two options in that deck. This guy pretty much invalidates DSC unless you're playing it AND wrath in the same deck.

tl;dr Prog>DSC in the 'win in two swings' department as pro swords>pro wrath