Endurance is a good fit here: it has flash, and it can be evoked by exiling a green card from hand when you can't spare the mana. Its enter trigger can make the opponent put their graveyard on the bottom of their library, which cuts delve fuel for Murktide Regent and delirium fuel for Dragon's Rage Channeler. Consign to Memory stays in the sideboard. Murktide Regent and nearly all of their spells are colored, so it would mostly hit Mishra's Bauble and a few triggered abilities. We shave Icetill Explorer, a slow four-mana value creature that can't keep pace with this deck's fast clock.