Eternal Bargain - FOREVER INSTITUTE

Oloro is the lifegain trigger champ that will make your dreams come true, as long as you can buy yourself enough time...whether on the battlefield or in the command zone, every single turn you will have a guaranteed 2 life gained.  On its own, this seems inconsequential, but for a combo-control (late game) player like yourself, you'll be slowing down other players until you can bust them up with an infinite life gain / damage dealt combo that will obliterate the playfield.  To do that, play both Exquisite Blood and Sanguine Bond onto the battlefield at once - with an easy and unassuming lifegain trigger (which Oloro and many other cards feature in this deck) to start up the infinite damage/lifegain loop!  Enlightened Tutor has been put in so you can find whichever one you're still missing, assuming you already got the first one. 

In case that win condition is eliminated, there are plenty of other late-game high-power cards that will also do the job just fine.  This is a slower deck; try to keep your head down and prevent yourself from becoming a target until you're ready to take on the entire battlefield at once.