Here's a hypothetical list, needs tweaking:
19 Lands
4 Delver
4 Shaman
4 Tarmogoyf
2 Tombstalker
4 FoW
4 Thoughtseize // Inquisition of Kozilek
3 Daze
2 Spell Pierce // Counterspell
4 Brainstorm
4 Ponder
4 Abrupt Decay
2 Ghastly Demise // Snuff Out
(Maybe adjust some slots to fit in singletons of Sylvan Library, Liliana of the Veil, go up to 20 lands, adjust the removal options and proportions, etc.)
Tombstalker is still great, but I don't know if the deck can really support more than 2-3. I think if you run stuff like
Predict or Thought Scour it's more reasonable to increase the number. But for this approach, he's just there to function as a big finisher that outsizes a ton of opposing decks' smaller threats.
Shaman is actually quite amazing. Beyond just mana fixing and accelerating into multiple plays in the early turns, he also gives you some reach and main-deck GY disruption. He can also help keep you out of Bolt range. When I was playing Team America some time ago, it seemed like Snapcaster recursion was a problem for the deck since they could just hit your dudes with removal over and over again. I know people will consider this card to be limited to playing Midrange/Control versions of BUG, but I think he may have a place in a more aggressive tempo version as well.
The rationale for playing a deck like this over RUG is the more versatile removal and having an increased edge against RUG, Counterbalance, and combo decks. You also gain access to some pretty sick SB options like Massacre, Dread of Night, Perish, Pernicious Deed, etc.