I am not convinced there was an implied agreement to preserve secondary market prices outside of the Reserved List, at least for cards which are Modern legal. As you mention in the article, one of Wizards' stated reasons for establishing the Modern format was to have a non-rotating format that wouldn't present a significant price barrier to entry. I think it's pretty clear that this constitutes an announcement by Wizards that there is no promise of value retention in Modern-legal cards, that what has been true for cards before Modern is no longer true. In this case, there isn't merely an omission of a verbal/written contract; there is a stated rejection of such a contract. Wizards essentially said, with the Modern format, "We are providing these cards but you are hereafter warned that they are open to reprint at any time."
That being said, I can't help but wonder if there is a point where enough time has gone by, much like a statute of limitations, where that original statement becomes invalid. Even though Wizards appeared to intend this to be the rule for Modern, they have not really lived up to that. Personally, I consider the low price barrier concept an essential point of having the format. However, we now live in a time when certain cards in Modern cost more than the expensive cards did in Legacy at the time when Modern was created.
I honestly think Wizards should consider banning cards from Modern purely based on their price having risen too high. Either that or do a real reprint of these cards (Modern Masters doesn't count because the price per pack still presents a significant price barrier).
In terms of play, I think it's generally worth it to "waste" a Detention Sphere on Underworld Connections. They tend to draw a ridiculous amount of card advantage from this over the course of the game. But it depends... If they have Pack Rat out and no verdict in hand, you probably have to go with that instead.
While that's true, the beauty of this particular combo is that Boros Reckoner and Boros Charm are both fully playable without the combo. You're basically building a RW aggro/burn thingy and it has a bonus of having this enchantment that can win the game by combo. The deck would not need to rely on the combo to win. This is what I think will make this viable.
Here's what's happened in my experience: You'll never get to prevent their Sphinx's Revelations. Any control player will treat this as a must-counter, must-remove at all costs. So be aware of that. That being said, being able to reliably strip away one of their counters or detention spheres is not that bad of a thing. You might want to play this a turn before dropping Elspeth or Aetherling with that strategy. And it does stop Mutavaults.
I've also used it to name Skullcrack a few times. About half of the time, they said afterward that they didn't draw a Skullcrack at all during the game anyway, or that they didn't even have it in the deck. Still a good play for RDW or Rakdos Cackler since few creatures in those decks can kill Council by themselves, and if they use a Shock to finish off the Council, you've at least pulled a 2-for-1 in your favor.
This makes a difference when it comes to not wanting to waste a card that relies on the other not being countered.
I'm inclined to think you can do either of the options I mentioned, but I've gotten a bit rusty on changes to stack/priority rules over the past 10 years.
I would say the list is going to be mostly creatures, because the "power creep" has generally meant stronger creatures and weaker non-creature spells, except that creatures tend to take a backseat in the eternal formats, which are much more dominated by control and combo. The creatures that do appear in older formats tend to used for combo effects rather than simply being efficiently costed. I think the list of candidates is going to be very short:
Pack Rat
Thoughtseize
Supreme Verdict
Sphinx's Revelation
Abrupt Decay
Voice of Resurgence
Scavenging Ooze
Shock-lands
I think all of these have appeared in some of the non-Standard decks that are at least Tier 2, and they are all pretty strong in Standard as well.
I think it's a great card and I had a couple in my sideboard until recently. The main issue I ended up having with it is that creatures are really the big threat against UW Control. If I really , absolutely must deal with a non-creature enchantment or artifact, I can use a Detention Sphere for that (to the best of my knowledge, no enchantments or artifacts in Standard have hexproof or protection from blue/white).
4 Temple of Enlightenment
4 Hallowed Fountain
4 Island
4 Plains
4 Mutavault
2 Elspeth, Sun's Champion
4 Jace, Architect of Thought
1 Aetherling
2 Divination
4 Supreme Verdict
4 Detention Sphere
4 Dissolve
2 Nullify
2 Syncopate
2 Last Breath
2 Celestial Flare
2 Quicken
4 Sphinx's Revelation
1 Elixir of Immortality
1 Blind Obedience
2 Celestial Flare
2 Last Breath
1 Council of the Absolute
1 Pithing Needle
2 Quicken
2 Divination
2 Jace, Memory Adept
2 Negate
Round 1 was against Gruul Midrange. I knew it would be a tough match, and it was my first loss. Made a critical error in game 3. I was at 7 and he had Boon Satyr out. I had 6 mana available. I could have played Elspeth, or I could have played Supreme Verdict and Blind Obedience. I went with the former, concluding that an Elspeth token could block the Boon Satyr and then I'd be on my way to building the victory army. Unfortunately, I forgot that bloodrushed Ghor-Clan Rampager also gives trample, which was just enough to get the 7 damage past one of the tokens. The other option would have been better. It would have at least been impossible for him to kill me on his next turn, as the blind obedience would stop any haste worries.
Round 2 was against A biomancer deck. It was a fairly easy 2-0 win, being somewhat combo oriented I just had to make sure I took out the biomancers with counters or Last Breath.
Round 3 was against UW Devotion (basically monoblue but with Ephara as well). This is a good matchup for me, as Last Breath works on almost everything in the deck. This was a 2-1 win.
Round 4 was against some kind of UBR control deck. I remember he got me once with Rakdos Return, but I won the match 2-1.
Round 5 was against Red Deck Wins. This turned out to be my 2nd loss, on game 3. I sideboarded really badly against this deck (I took out my Verdicts seeing only 1 creature each of the first two games, and then lost the ability to get rid of his creatures on game 3), and realized I didn't really have what I needed in the sideboard to begin with (Fiendslayer Paladin).
Then it got kind of silly. Round 6, my opponent didn't show up. So I got a win. Then in round 7, the same thing happened. I was now 5-2, where one more win would earn me 1/2 booster box.
Round 8 was a mirror match. I sideboarded very badly here, falling for the old mistake of sideboarding against the maindeck rather than sideboarding in preparation for opponent's sideboarding. I took out Celestial Flare, Nullify, and Supreme Verdict, and he played 2 blood barons. He was also much more skilled at playing the control archetype than I currently am.
In spite of the losses, I still feel pretty good. I had hoped no better than 50/50. And I was able to identify the mistakes I made, which hopefully will help in avoiding them in the future.
A few changes to the sideboard after this event. I took out the 2 extra Quicken, and I'm replacing those with Fiendslayer Paladins, which should be good against RDW, Rakdos Aggro, and the newcomer deck monoblack aggro. Quicken is great, but I will just have to play it differently. It's good when facing Stormbreath Dragon, Mistcutter Hydra, and especially Obzedat, but I will have to stop cycling them for draw and just hold onto them until I need them (and have the verdict in hand). Only 1 Jace Memory Adept now, and bumped the Council of the Absolute up to 2. So I know this card is not a popular choice, but here's what happened. I played it against the mirror match (for Rev), the biomancer deck (for the biomancer), and the UBR Control (in fear of Slaughter Games). It got countered every time, so it never really got to do what it was meant to do, however if it seems to invoke that much fear in my opponent then I think playing it is the right choice. I'll try it for a while before I make up my final opinion on the card. Also, the deck was supposed to have 5 Islands and 3 Plains. That's been corrected.
EDIT: And I only just now noticed that Council of the Absolute cannot name creatures, so my plan for the biomancer would not have worked even if it had not been countered.
1. When to counter something vs. letting it go to deal with later. I seem to always make the wrong decision here. One of them I never quite feel sure about is an opposing Sphin'x Rev at the end of my turn. I could counter it, but that leaves me tapped out on my opponent's turn, which could be a critical error that determines the outcome of the game. Usually I'm in favor of countering it, though, just because of how strong the card is. What about smaller draw spells, like Divination? Counter or no? I usually don't. Sometimes I decide not to counter something because I figure I will just use the Detention Sphere in hand and I can then save the counter for something that can't be Detention Sphered (like a non-permanent or something with pro-blue, pro-white, or hexproof). But it seems like I often make the wrong call on this, misjudging whether or not I can safely allocate the mana for the Detention Sphere the following turn.
2. Making idiot mistakes. For example, there was a time I let a major threat go uncountered because I had planned to Supreme Verdict the next turn anyway, but when it got to my turn I realized I only had 1 source of white mana available. Another time, I had Aetherling out and I used Sphinx's Revelation at my opponents EOT tapping out completely, which prompted my opponent to use Hero's Downfall on my Aetherling. Obviously I know that's the wrong thing to do, but how do you avoid forgetting things like that?
3. Against other control decks, when is it safe to play a threat? It seems like if I play the first threat, it typically goes that I wait until I have enough mana for the threat plus counter... they counter my threat, I counter, they counter again. I end up with nothing on the board and I'm tapped out for their turn. They usually follow up with their own threat like Aetherling and that's pretty much game.
Thanks for any advice. I know part of being a better player is playing more, but I honestly feel like I'm not learning from my own mistakes very well. There are mistakes I'm likely making that I am not realizing. I aim to be a competitive player but I feel like I have a ways to go, even if I am playing a good deck.
There are combos in the format, and they aren't really worse than older combos. For example, the Elite Arcanist + Triton Tactics + Zhur-taa Druid combo is an instant kill combo. But it's too slow to win before aggro decks will win, and the increase in creature power has corresponded to an increase in creature removal, and it's vulnerable to that as well. The most playable infinite combo is probably the infinite life Boros Reckoner combo, because all three cards in the combo are competitive-playable without the combo.
Maze's End is also technically combo, and it has placed in a recent event listed on tcgplayer.