Your signets along with Black Market will help you build a solid mana base, too
Swarmyard Massacre might be the most powerful of the new cards in this precon
Working to get its power up to 3 before you can start copying spells is a bit of a pain, especially if the implication is youll be burning your instants and sorceries to temporarily buff Kitsa before copying those spells
We'll want this Elemental here since it's a huge win con five-drop equal to your land count and your nontoken stuff counts as Forests to grow its size and tap for that mana
Looking at the black cards with destroy in the text, heres what I chose to add: Cut Down, Go for the Throat, and Shoot the Sheriff provide excellent and efficient creature removal spells
Even with the tokens from Myriad coming in tapped, and only lasting until the end of combat, you can easily pop off