The hype train for the Magic core set has begun and I have to admit: I like what I'm seeing.
Warden of the Beyond is my; 'No, no don't do that', card of the week and here's why:
Magic needs a place where cards go and are never heard from or interacted with again.
Now that the game is twenty years old it's changed quite a bit and by now, a place like the graveyard just isn't the graveyard anymore. Many decks have interactions with it, from very small ones, like Threshold or the power/toughness of Tarmogoyf to being based wholly around it, as the Dredge or Reanimator decks are.
The two other zones in Magic where cards go to be excised from the game are the Command zone, used for Planeswalker emblems, Conspiracy cards and Commanders. Commanders are the only ones that really interact with the Command zone, being able to re-enter the game at will from there (assuming you can pay, of course). Wizards has recently experimented with having creatures that have abilities that are relevant to the Command zone and from what I've read at the Reddit community, many (like me) are not fond of what cards like Oloro or Derevi do to the Commander format. The impact that cards you cannot interact have on the game is generally considered to be a negative one and with good reason: decreasing interactions makes games boring.
And then there's Exile. Cards that are put into Exile are meant to be absolutely gone forever. Then they printed Misthollow Griffin.
Sigh. I get that there are very few absolutes in Magic but this should be one of them. Cards sent to Exile should no longer interact with the game.
I'll give Wizards this: Warden of the Beyond is in the appropriate color, because White has more Exile effects than any other color I am aware of. However, the doors have been opened, now. We have cards that are interacting with what should be a dead zone and I'm going to argue that this is bad for the game because it is another step towards turning the Exile zone into another Graveyard. Since we already have the Graveyard, we don't need another and while they can mock the idea all they want, if Wizards continues to become more hands on with the Exile zone, the more they are going to need to establish a fourth zone.
We don't need a fourth zone.