Gurmag Angler is, I feel, mandatory for any delve deck. Moreso than Sibsig Host, who could be easily replaced by Taigam's Scheming. +1, I'm glad to see someone still trying to make a sultai delve deck.

Definitely some of the new lands such as Sunken Hollow or Lumbering Falls fetch lands are hard to get because of cost but definitely would benefit with the delving. Murderous Cut is too good to not main board.Crux of Fate Dead Drop semi wipe the field and potentially feed the delve and Monastery Siege Also gives card advantage and feeds the delve. Soulflayer Necropolis Fiend and Kheru Lich Lord are good with delve, but the most you could get with Soulflayer is flying and deathtouch. Dutiful Return can add a good card in hand to scare them and also Den Protector and Deathmist Raptor are good with the grave. Sultai was the first 3 color combo I made and I will always be partial to it +1