Although the new Extended rotation policy means that Onslaught gets to stick around for one more year, the extensive drop-off as October, 2008 rolls around means that two key players in the Extended disruption suite will be departing.

These key disruption spells offered a chance to put someone off their game plan on turn one, and, in the case of Therapy, to completely obliterate their game plan either via Flashback or via Duress into Therapy. Ugly.
Although Shards may well bring some good disruption options, it’s fun to think about what’s already available to us in the world of Onslaught Extended.
Full thoughts in the extended.

First turn all-stars
Extended disruption wants to happen on the first turn. The first turn is when you get to rip options out of the opponent’s hand unopposed, especially if you’re on the play. Turn one is when you’re probably not doing anything else anyway, if you’re running a deck with disruption. As Rich Hagon has commented, when playing Extended, always imagine your hand without its best card, because someone is going to take it from you before you even get a chance to play it.
So what are our turn one options?
Thoughtseize – The obvious standout. This recent Extended season saw players happily knocking off a quarter of their life total on the first-turn play of fetchland into shockland into Thoughtseize. Incredibly flexible, Thoughtseize lets you immediately go to work on the opponent’s game plan, yanking out creatures and spells with impunity. Clearly good.
After Thoughtseize, we’re only left with three somewhat conditional first-turn options.
Blackmail – Feel like Thoughtseizing the lesser half of your opponent’s hand, but not paying life for it? In an environment with Therapy, Duress, and Seize, Blackmail was left out in the cold. Perhaps it’ll come in with two thirds of those options gone, but it’s still on the weak side.
Shattered Dreams – I could see this getting actual play, depending on the environment. Yanking away an opponent’s Top on turn one is not at all a bad thing, nor is clearing out a Jitte or a Sundering Titan. That said, it’s probably a sideboard card at best, as a Zoo or Red Deck Wins player doesn’t mind at all that you’re groping around blindly in the dark for artifacts that aren’t there, instead of making a relevant play.
Psychic Spear – I almost didn’t include this out of its likely sheer irrelevance, but I suppose that in a post-Shadowmoor world, there may be critically relevant spirits that the Spear can target. I can’t imagine the Arcane side of things ever being especially relevant, though. Great card in Kamigawa OWE cube draft.
Showing up a turn late
Until I played with Distress in one of my Lowryn-Standard Rock decks in Magic Online, I did not appreciate how bad a two-mana, targeted discard spell really is. It feels a little shocking that it should matter so much, but that second mana means that you can’t hit on turn one and you can’t lead into other plays with a discard to bait counters. Even so, there may be room for these cards now that the turn one options are so much more limited.
Castigate – Possibly the leader among two-mana discard options, Castigate has the strength of RFGing the card rather than forcing a simple discard. As such, you can RFG potential recusion annoyances (e.g. Mindslaver) and get added value over conventional discard. On the other hand, you never get to Extirpate the targeted card, but that’s probably okay. Notably, with the loss of all but the shiniest of Wishes as we go into Onslaught Extended, RFGing something out of a combo deck becomes an especially powerful option.
Rise // Fall – The Fall portion is the closest we’ll come in modern Magic to a Hymn to Tourach, nailing two non-land cards at random for two mana. The colors here don’t mesh well with most current Extended decks that pack disruption, but going into the future, one never knows. Perhaps a deck with Thoughtseize, Rise // Fall, and Void will be viable.
Distress – Thoughtseize, giving back the 2 life in exchange for a critical black mana. In my experience, Distress has not been a particularly solid option. Perhaps it’ll play backup to Thoughtseize if no better options come along.
Chain of Smog – Two cards for two mana, as long as you’re okay with having it done right back to you. This kind of game plan relies heavily on your own plan basically being entirely resilient to disruption.
Wrench Mind – Two cards for two mana, unless your opponent pitches an artifact. This feels potentially relevant, although the fact that it is neither targeted nor random points toward why it’s not in use generally. It’s damaging, but especially in Extended, may not keep your opponent off their game plan.
Perhaps too expensive
Stupor – Half Hymn, half Mind Rot, Stupor showed up to some extent in the most recent Standard season. At three mana, it’s an awfully late-game appearance for a card whose major claim to value is its single random discard. It’s there, but probably not viable.
Nightmare Void – A four-mana Thoughseize seems like it’s not at all the value, but the ability to recur it over and over again via Dredge means this might be a nice late-game play against reactive control. “Nightmare Void.” “Counter that.” “Nightmare Void again.” Like that. Still, as we’ll see below, there are two four-mana options that have the potential to be far more destructive than the point discard of Nightmare Void.
Blowing up the world
Cranial Extraction – As I’ve mentioned already, I do adore this card. Extraction can put an opponent off their game plan in a way Thoughtseize can’t even hope to, assuming you can make it to four mana in time. If you know the decks in the format, you can cripple many of the combo and control options with a single Extraction. Turn three Extraction for Form put me on the winning path against Enduring Ideal in game three of a match I played in the last PTQ; later in the same day, recurring Extractions stripped nearly all the threats from a Tooth and Nail deck, making for a much easier kill.
Persecute – At Regionals last year, I was running Persecute. At four mana, it’s kind of chunky for Extended…but as we roll into late 2008 and lose everything ahead of Onslaught, Persecute may once again be a viable way to decimate someone’s hand. With all the acceleration in the format, a turn-three Persecute is simultaneously devastating and not at all out of the question. Unlike Extraction, where you might want to run anywhere from two to four copies, you pretty much always want to run four Persecutes so you can slap one down as soon as possible.
Void – At five mana and in a somewhat awkward color combination, Void’s utility in Extended is questionable. That said, Extended is also a format that sees decks running a lot of cards in the 1-2-3-mana range. Thus the power of Counterbalance-Top. As another player said at a casual Magic event I attended last month, a Void for three would do serious harm to a typical Doran deck from the current Extended season.
Mind Shatter – Expensive. This starts being real value at maybe five mana, and probably at six or more. On the plus side, it is random discard, and it does improve as you go into the late game, much like Profane Command.
So there you go. From Seize to Shatter, these are the primary options (and probably some terrible options) that we’ll be thinking about as Extended rolls over in October of this year.
I’m glad we’ll still have Extraction.