From SpongeBob SquarePants to The Lord of the Rings, Warhammer 40K, and Dungeons & Dragons, Wizards of the Coast has taken advantage of its partnerships to ensure that players are receiving quality collaborations, and thus vibrant new decks
We already know that Regal Caracal is goodit saw a lot of play back in Amonkhet Standard a few years ago, even as a standalone card in non-Cat decks
Esper Esper, then, is an ally of Grixis, and must have some overlap to keep things balanced
Still, this one has its uses
I think that if you wanted to have a discard spell in the sideboard you would probably just want to be playing seven in the main deck, but if you did choose to put one in the sideboard it should be a Duress
This deck goes deep into greens land synergies to assemble powerful wincons that teach your opponents the value of interacting with a mana base via Demolition Field and Strip Mine