Here's my take on
spider spawning; compared to other lists I saw in this thread it seems more focused on self-milling and less on alternative strategies (such as reanimation); for example I'm running 4 tome scours to good success
3
hedron crab4
tome scour4
think twice1
negate3
guard gomazoa2
archaeomancer1
fog2
elvish visionary4
satyr wayfinder1
beastmaster ascension2
saruli gatekeepers3
spider spawning2
nemesis of mortals1
shadowborn demon3
treasured find5 island
2 swamp
5 forest
12 guildgates
An unanswered crab is basically unbeatable, but we only get 3 fragile copies of that crustacean miracle of nature; so the deck tries to get as many crabs as possible by milling them with scour/satyr and replaying them through treasured find - or drawing them by flashing back think twice.
This is why rescue from the underworld got cut: I would just use it to get back the crab 90% of the time (not kidding), and for that treasured find is cheaper - even using archaeomancer for treasured find for crab is very reasonable.
Eventually spider spawning happens, I grab the singleton ascension from the graveyard and attack for lethal.
I have zero interaction with my opponent's creatures but I can repeatedly cast the single fog if needed, while digging with the crabs and think twices.
Also, I cut the necromancer's assistants since they are worse at milling than tome scour; as blockers they are very inefficient against the fast decks (spend 3 mana to trade with a goblin token?), which are the only matchups where I need blockers in the first place. If I wanted more mill (and maybe I do ) I would seriously look at the 3 mana sorcery that mills 5 before considering them.
Edit: I realized that
siege dragon exists and I had no way in the deck to deal with it. So I cut a nemesis for a shadowborn demon, which is also a good way to stabilize the game while waiting to get to 7 mana to flashback spawning. As for the nemesis, it's in the deck mostly as a cheap blocker that teams up with the gomazoa and the gatekeepers to slow down the opponent, and occasionally turns into a win condition (when it's the only creature surviving an
anger of the gods). It doesn't feel 100% necessary, but it has been good so far.