(I'd encourage you to check out the sheet, if you haven't already, if you want to see all of the individual card prices that make up the expected value.) Secondly, Double Masters is a massive set with 40 mythics and 121 rares, and especially considering the spreadsheet already lists everything out, it's just not worth putting every individual price into this article
The value of X is calculated only once, as Sanar's ability resolves
For the love of the seven brass gods, its a city of academics
Decks that want to play counters are almost always control decks, and control decks would much prefer to gain life rather than cause opponents to lose life, so all things being equal they would have preferred to play with Absorb but there were other considerations that forced most of them down the black road instead
Brunos eyes glow purple and his face is encrusted in barnacles as he looks into a prophecy tablet showing the three again
Assuming that you don't have any cards in your graveyard, it will exile your entire library and you can win the game via Labratory Maniac, Jace, Wielder of Mysteries, and Thassa's Oracle