If you are looking to invest in a Reserve List card thats going to have a high price tag initially, but I cant conceive will ever drop down, The Abyss is it
With QPMN, you can replicate this allure using Print-on-Demand Holographic Cards
With the Fully Charged ability youll pay one ink less to play it so long as you have an Inventor character out
This makes for a fundamentally riskier style of gameplay, as getting a rough starting draw (a gamble alleviated somewhat by the fact that the rules allow a redraw attempt) can make it difficult to get off the ground
Liliana of the Veil The best black planeswalker of all time, Liliana of the Veil benefits from a low cost and three versatile abilities that make her very useful in multiple formats - especially Modern
The other obvious improvements would be more of the same good Pirate cards already in the deck, and Piglet Pooh Pirate Captain