I saw a deck trying to make Twitching Doll and Agatha's Soul Cauldron a thing, and I'm curious to try building around it.
The two other elements you need is a way to put +1/+1 counters on the spider tokens, and some way to give haste to the spider tokens. Preferably green-friendly to make the Doll easier to play, but you could splash green easily enough. Once you have all the elements, anything that has a +1/+1 counter on it has Doll abilities, and activating the Doll sac on a creature spawns one or more spiders, each getting +1/+1 counters from the Tribute. Go infinite all you like.
I'm interested in Tribute to the World Tree for the counters, and I think Yarus, Roar of the Old Gods is worth a try as a haste enabler. Yarus kind of opens the door to a Manifest Dread angle I'm curious to try. Dread actions helps put good cards in the graveyard for the Cauldron, and Yarus enables flipping a Cauldron that was Dreaded.
So the Dread enablers I'm interested in are Threats Around Every Corner for the extra ramp, Hauntwoods Shrieker for value Dreading and cheap flips, and Valgavoth's Onslaught for burst Dreading and a bit of finishing power with the extra tokens.
I'm also interested in a couple Backup creatures Doomskar Warrior for some extra digging and Voldaren Thrillseeker for the obvious game-ending synergies.
Overall it seems fine, but it is slow. It does some fun powerful things along the way, but probably falls short next to what else you can do in this meta.
