One idea I want to test going forward is
Sandwurm Convergence in the Ugin Slot. I like that you can Show and Tell it in and think it might help the Grixis Delver matchup because it let's us clog up the ground while also stopping air attacks and Grixis struggles to answer enchantments. It also sounds quite nice versus Reanimator, Sneak and Show, and Marit Lage decks. I have tested it once against Miracles. It won the game, but didn't particularly shine in this matchup. I did find the double green hard to get, making me cast it a few turns later than I could have cast an Ugin.