I got the idea from Darkest Hour and Light of Day to prevent all combat so black/white life leeching creatures such as Agent of Masks, Orzhov Guildmage, and Ghost Council of Orzhova (which were in here) along with Teysa, Orzhov Scion, Darkest Hour, and Twilight Drover for undying tokens for shenanigans with Thoughtpicker Witch and Ghost Council, but it was too unwieldy.
After playtesting it, I trimmed it down to what it is now. Now, If the combo doesn't have trouble going off, it can halt aggressive creature decks in their tracks, including the more vicious sliver decks, and I end up with a rather large amount of flying black 1/1 spirits and a large X+1/X+1 Twilight Drover or two, where X is how many times the spirits have died due to combat or as food for the Thoughtpicker Witch. It is much more aggressive than its first incarnation due to all the spirit spammed, and cards like Thoughtpicker Witch, Hissing Miasma, Order of the Stars, and Batwing Brume allow me to stall if necessary to get it off. Beckon Apparition and Raise the Alarm are there to assure that I get the tokens I need, while Dimir Machinations locates for me Teysa, Orzhov Scion, Twilight Drover, or maybe a Hissing Miasma, depending on what I need at the time.
When it works, it falls into place well, and when it fails, it takes a while to die, so you can try to stall for a victory (including a time where I didn't have Teysa, Orzhov Scion, Twilight Drover, or Darkest Hour out and I won due to Hissing Miasma and Batwing Brume along with a few tokens).