In short these days, its really not too difficult to build a Commander deck that allows you to fully unleash Exavas power
The times it has shone, it was a game changer, especially in Esper decks with Raffine, Scheming Seer
Alternatively, she can spawn a second, weaker creature for -2 once you've put something onto the battlefield
Excepting that, youll probably want to have some You Did This to Yourself elements handy
Bloodline Necromancer Bloodline Necromancer is a prime example of a creature that gets a boost from lifelink, even though it has nothing to do with the other abilities
Make sure you have enough graveyard recursion, re-shuffle cards like Enhanced Survillance, Feldon's Cane or Finale of Revelation, or anti-mill win conditions like Laboratory Maniac as backup plans for when you surveil a bit too vigorously