Standard Metagame Analysis
We're at the end of Return To Ravnica - Theros standard - The format has changed, evolved, devolved, changed and then finally stabilized with a few top tier decks. While which deck is the best each week is in constant flux, the format has mostly been solved, and that solution is rooted in a few unreasonably powerful cards.
These three pillars of the format show up in all of the top tier decks. They are the backbones of the format, and if you are looking to compete, you cannot play a deck that has no way to answer or play around these cards.
Thoughtseize is a reprint, and is the single most powerful discard spell in the history of Magic. The ability to strip your opponent's hand of their best card for the cost of one black mana and 2 life is, bluntly, overpowered. In addition, you are given a look at your opponents hand, allowing you to act with perfect information. What more could you possibly ask for?
In any case, Thoughtseize is, of course, very prevalent here at Pro Tour Magic 2015. I do not believe it would be an exaggeration to say that roughly 50% of the decks in the field feature Thoughtseize somewhere in their 75. If that's not a metagame domination, I'm not sure what is.
Mutavault is considerably more innocuous than Thoughtseize, but is easily on the same power level. Creature-lands are often heavily undervalued for the ability to manage Mana-flooding. Games where you draw too many lands can easily be salvaged if those lands also kill your opponent. In addition to giving you something to do with your extra mana, Mutavault also dodges all sorcery speed removal (barring a Quicken in to Supreme Verdict), takes out opposing planeswalkers and protects your own. It provides a way for aggressive Red Decks, like the deck played by some Channel Fireball members this weekend, to eek out the last few points of damage while still being able to be tapped to cast actual spells. Mutavault is another card that appears in at least 50% of the performing decks this weekend.
Finally, the third pillar of Standard - Sphinx's Revelation. Originally thought to be another bulk mythic, it turns out that tacking on life gain to Blue Sun's Zenith was all that was necessary to turn the tempo-negative card in to a format all-star. While Sphinx's Revelation is played in considerably fewer decks than the other two cards, it's sheer power and the fact that Blue/White/x decks have dominated the last 2 years is the reason it is the third pillar of Standard. If you're in the market for countering/removing your opponents first few plays, then drowning them in card advantage from combing massive card draw with life gain, then Sphinx's Revelation is your card. I would be very surprised to not see a Sphinx's Revelation-deck in the Top 8 this weekend!