A [Platinum Angel](http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=425817) and [Laboratory Maniac](http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=230788) for both players would take care of most game endings but either one could be removed from play in a variety of ways. [Mycosynth Lattice](http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=50527) and [Darksteel Forge](http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=370734) would negate combat damage and destroy effects but not exile or sacrifice effects.

Edit: Ideally, fo maximum troll the boardstate should be reachable with only one player working towards it.