Historic Scholar Combo
This list comes from a Magic brewer who wishes to remain anonymous. There are quite a few cool things going on.
The main idea is to mill yourself as much as possible with cards like Stitcher’s Supplier and Merfolk Secretkeeper and use card draw spells like Chart a Course, Strategic Planning and Thirst for Meaning to set up a graveyard with Scholar of the Lost Trove, Unburial Rites and Emergent Ultimatum. Ideally, you can do this by turn four when you can already flashback Unburial Rites from the graveyard, target the Scholar and use its ability to cast the Ultimatum from your graveyard for free.
If the opponent chooses Gravebreaker and Scholar, you cast Gravebreaker first, get another Ultimatum in the graveyard and then cast Scholar to flash it back for free and go again. Otherwise, if they choose Sublime Epiphany and Gravebreaker, you cast the Gravebraker first to put another Ultimatum in your graveyard and then use Sublime to copy your Scholar to go again. With Scholar and Sublime Epiphany, you can just use Scholar on something that’s already in your graveyard, like another Ultimatum or Alrund’s Epiphany and then use Sublime to make another copy of Scholar and draw a card, which is going to let you flashback the Sublime again to make yet another copy and draw another card.
There are quite a few possibilities every time you cast an Emergent Ultimatum, so just do whatever feels right in the situation. Historic is a huge format so I’m sure there are some other possible Ultimatum targets you can run as well.
This deck’s problems are going to be super fast draws backed up by Thoughtseize and sideboard cards like Grafdigger’s Cage and Rest in Peace. For those reasons, it might be better to stick to the Best-of-One format.