Temple of Enlightenment

So I feel like we should discuss how this will be the card that makes U/W just the flat-out best control deck of choice, without knowing anything else from BNG yet. U/W gets the best mana base and its removal is still barely worse than Esper's or UWR's. In reality expensive catch-alls aren't very efficient, so the extra colours really don't help too much. Sure, UWR has Counterflux and Assemble, and Esper gets Blood Baron, but UW already has the best late game in the format, and this gives it an even better edge in the best mana base department.

Esper has a lot more than just Blood Baron, but I digress.

This existing allows for U/W(/x) to exist in the format and at least do something.

Esper doesn't actually gain a lot other than Blood Baron though. It gets Hero's Downfall which is a very restrictive, colour intensive Detention Sphere. It gets Dimir Charm which is a barely more flexible Last Breath. It gets Thoughtseize which it can't even make the best use of given its lack of pressure and the length of game it plays. So I wouldn't say it doesn't just get Blood Baron.

U/W is already doing something.

I just feel like it needs a third color to do more. *shrug*

Do more what? It has counters, removal, the best sweeper and draw cards in the format. The best finisher. The best late game. The most resiliency to hand disruption. What more does it need?