Grist, the Hunger Tide Grist, the Hunger Tide is here to meet us as the only planeswalker commander on todays rankings
Cascade is a cast trigger so you cannot cheat it out, recur it, or blink it and net the cascades
Mill decks are designed to win the game by running your opponent out of cards, which either loses them the game immediately, or loses them the game indirectly, since they no longer have any cards to play against you - depending on what card game youre playing
Forget about Standard, I would be surprised if this wasn't playable in Modern - at least as a sideboard option for dealing with artifact/enchantment heavy decks
Gengar brings decades of popularity and competitive relevance, while Mimikyu adds emotional depth through its design and lore
It only affects Luxray, so its less of an issue here than in, say, the Tinkaton ex deck but still, its definitely something to bear in mind if you have this deck and want to modify it yourself