The question is if thats worth being in an energy deck in Modern
You can, of course, play with a mono-black deck, in which case you would want to opt for a mono-black booster box if you can find one, or a least a box known for strong black cards
The card includes 11 different Oracle rulings to go along with the words that are actually on the card, covering myriad potential questions about exile, cage counters, and what happens if multiple cards with the same ability are exiled with the aforementioned cage counters (Mairsil will have multiple instances of that ability
Order a few extra basics/tokens if youre rebuilding lists often
The four-drop enchantment in Green you become the monarch and in your upkeep you can drop any land to play from your hand, and a dork too if you are the monarch which isn't needed at all here
From the grave, to the grave, so goes the black magic