Flavor-wise, Mirror Universe imagines the players as reflections of one another, and these reflections might change
This creature effectively allows you to play a traditional aggro game where you swarm the board with cheap creatures and finishes things while your opponents fiddle around with Talismans and such, and greens deep pool of proliferate abilities gives the deck late game burn
There are a ton of good pieces to make a graveyard deck work in Standard, which would be the best home for Invasion of Shandalar, but so far, no one has made the archetype work
Next up is Cathartic Reunion, which is another solid way to get big threats from our hand into our graveyard while also being card-neutral (unlike Faithless Looting, which leaves us down a card), although counterspells can be a blowout, since discarding two cards is part of the sorcery's casting cost