For a deck that's basically a mostly white deck with a splash of black for Sanguine Bond and some green for Shalai activations, Arcane Sanctum makes no sense. (Only as a poor dual land for w/b, but you can do better with uncommon and even common lands.) The triland you want here is Sandsteppe Citadel, if you want one. Though I think, you can do better. Like Urborg, Tomb of Yawgmoth which allows all your plains to tap for black mana and thus you need only one "Swamp" to get the double black. Maybe run Chromatic Lantern to get double green as well alongside some ramp.
Since you can accumulate lots of life, maybe invest some of it into cards. Black is notorious for getting cards for life (e.e. Liliana's Contract). Those cards are worth it, they will keep your hand full and you in the game. Overall, since you have already dipped into black, go deeper, there are many good things there, and with a mana base able to produce BB single black cards are already well supported. For example, you can gain life for killing stuff, very useful, more so than cards that just gain you life.
15x Plains
5x Swamp
4x Arcane Sanctum
1x Orzhov Basilica
Spells(38)
4x Shalai,Voice of Plenty
4x Voice of All
4x Commander Eesha
4x Rhox Faithmender
3x Mother of Runes
2x Beloved Chaplain
2x Felidar Sovereign
3x Celestial Mantle
4x Beacon of Immortality
3x Congregate
3x Sanguine Bond
1x Ajani, Caller of the Pride
1x Sol Ring
You probably know about the Sanguine Bond+Exquisite Blood combo, but if not, just throwing it out there.
If Sanguine Bond is a key piece for the deck, you want four, and maybe some Defiant Bloodlords as well.
Since you can accumulate lots of life, maybe invest some of it into cards. Black is notorious for getting cards for life (e.e. Liliana's Contract). Those cards are worth it, they will keep your hand full and you in the game. Overall, since you have already dipped into black, go deeper, there are many good things there, and with a mana base able to produce BB single black cards are already well supported. For example, you can gain life for killing stuff, very useful, more so than cards that just gain you life.
Former Rules Advisor
"Everything's better with pirates." - Lodge
(The Gamers: Dorkness Rising)
"Any sufficiently analyzed magic is indistinguishable from science."
(Girl Genius - Fairy Tale Theater Break - Cinderella, end of volume 8)