Right now Boros and Valkut Ramp are very powerful and almost near unbeatable there are few cards in standard that take care of either situation..
With Hero of BladeHold and Hero of Oxid Ridge Boros is now going to be the top deck and kill you way faster than it normally would have! Turn 4 day is now obsolete in Blue/White control!! or any other White control deck you have to run Black to situate yourself for the first 4 turns and even then they will come back hitting harder with more Heroes!!!
Valkut ramp in the new set has Thrun the Last Troll!! With this on the field the only thing able to take care of him is a Day of Judgement but only when he doesn't have mana untapped which is rarely because he can just regenerate him You can't counter him you can't target him and you can't kill him haha he is a big 4/4 on the field for the rest of the game and added with the Green Titan he won't be going anywhere!!
Combos!
Valkut Ramp
Turn 4 or maybe even turn 3 with Summoning Traps Primeval Titan comes out searching
for 2 Molten pinnicales making the 3 mountains on your field already available or
if you had 4 then next turn you hit for 6 search for 2 mountains play them that deals
12 damage and then the mountain drop you have gives an added 3 and if you had a harrow
in your had that's another 12 damage.. all because of a land with lack of "Destroy Land"
cards... Thrun is your safety card he will win you the game almost always!
That is overkill unless you are wasting mana and rephase on life which is useless if you can't stop it!
Boros Red White
Turn 1 you play your goblin guide and swing for 2
turn 2 you play another swinging for 4 that's 6 so far
turn 3 play a signal pest hit for another 4 that is 10
turn play 4 Hero of Oxid Ridge hits the field swing all out for 14 that is a total of 24 if he had a wall of omens
that would have blocked 4 damage you are dead unless you went first and played a day turn 4 living with 10 life!
InkMoth Shape Anew Deck
This is a heavy hitter due to the fact it speaks for itself you control the whole game until you get to shape anew turn 5
pay 1 and use that one to turn your inkmoth into an artifact shape anew that with the only artifact you are running being BlightSteel infect deals damage in poison counters a player only needs 10 to lose therefore he kills you the turn after with one hit he cannot be destroyed the onlything able to destroy him is to exile him!
just incase they are running black you can run the Duress to look into their hand the turn before and get rid of this card
I've played against all 3 of these decks at FNM with my Black/White control I have won because I know how to play them
but they are pumped and much harder to take down than a normal deck 0/4 games you will win against these if you
aren't prepared. I've lost so many more times though to them.