Hazoret's Undying Fury
Oracle Text
Shuffle your library, then exile the top four cards. You may cast any number of nonland cards with converted mana cost 5 or less from among them without paying their mana costs. Lands you control don't untap during your next untap step.
Card Rulings
7/14/2017 Each individual spell you cast this way must have converted mana cost 5 or less. Their total converted mana cost could be greater.
7/14/2017 No player may take any actions between the time you shuffle your library and the time you exile the top four cards.
7/14/2017 If you cast a card “without paying its mana cost,” you can’t choose to cast it for any alternative costs, such as emerge costs. You can, however, pay additional costs. If the card has any mandatory additional costs, such as that of Tormenting Voice, you must pay those to cast the card.
7/14/2017 If the card has in its mana cost, you must choose 0 as the value of X when casting it without paying its mana cost.
7/14/2017 If any abilities trigger as you cast any of those cards, they won’t be put on the stack until after you’re done casting them. They’ll resolve before any of those spells.
7/14/2017 If you cast any of those cards, you do so as part of the resolution of Hazoret’s Undying Fury. You can’t wait to cast them later in the turn.
7/14/2017 If a spell you cast this way targets another spell, it may target a spell you cast earlier during the resolution of Hazoret’s Undying Fury. It may target Hazoret’s Undying Fury as well, but Hazoret’s Undying Fury will be put into your graveyard soon afterwards and the spell’s target will become illegal.
7/14/2017 No lands that you control will untap during your next untap step, even lands that aren’t tapped as this spell resolves. This includes lands that enter the battlefield after this spell resolves.
7/14/2017 If more than one spell says that lands you control don’t untap during your next untap step, the effects will all wear off during that untap step. You’ll untap lands you control during your untap step after that one.
EDIT: According to the rules:
202.3b When calculating the converted mana cost of an object with {X} in its mana cost, X is treated as 0 while the object is not on the stack, and X is treated as the number chosen for it while the object is on the stack.
And surge is an alternate cost as long as you've played a spell. So if you reveal Fall of the Titans not only can you play it, but you should be able to play it with the alternate cost of X=4 (CMC=5). Can I get a confirmation?
EDIT: I looked up the surge rules and this one is a no-go.
If they made the card to easy to use it would just become the go to win con and red deck wins would happen again.
"Shuffle your library, then exile..."
2. Card advantage on average is more powerful than mana efficiency so even if you don't make up the mana cost there is a good chance you pull ahead anyway because not only did you look at four cards but you got to play 2 (average in a deck built around this)
3. Remember when everyone was talking about how bad Collected Company and Aetherworks Marvel were "So you have to pay 4 mana and all you get is 2 creatures IF you hit something and they can only be 3 mana or less pfft that will be fringe playable at best" and lets not forget "so I have to spend my turn 4 doing nothing just to play an artifact that I then have to work to then potentially miss anything worth playing that wont break standard at all"
Look I am not necessarily saying it will be that good I'm just saying that cards that let you look for other cards to then cast for FREE have this tendency to be told they suck only to later find out "oh yeah they make you spend mana on cards for a reason"