Starting from the top:

aholder7 Infernal Tutor is used to pull more orchards but i also pull more copies of Blood artist. That is the primary use for the tutor. the more copies if blood artist i get to the field the more dangerous it is for the opponent to board wipe. Secondary use is to pull a card that i need when i have no hand, which happens allot strangely enough. Now Bout the other suggestions you had. Why i chose Blood Seeker over Suture Priest and why im running Sylvan Scrying and not more Serum Visions purely comes down to mana base. The current mana base supports more black than white and more green than blue. That is the simple answer. I will test out a different mana base on a private copy of the deck that i have and see if a re-balance can be worked out to make these subtle changes.

CharonSquared Ill be honest i think i was testing Murder Investigation out for play ability the last time i was working on the deck. But it is a dead card so > Changed M.I. to Path to Exile

Lifa Virulent Plague is necessary to the build. Without Plague or Illness in the ranks, this deck will not work. the ability is too key of a component to not increase my odds of having it. Path to Exile has been added in lue of Murder Investigation. Murmuring Bosk is a strange card to be sure to have in the build. The main reason i chose this over your suggested 2 is that Bosk can be fetched as needed. If i were to sub it out id go for a copy of Temple Garden for the same reason. Both lands you suggested are good cards, just not as a one of. My mana base is shifting a bit from the looks of it so im not going to rule either of them out yet.

To all: Thanks for the suggestions ill look into the changes.