Previously, a token was owned by the controller of the card that created it. For example, if I dropped Hunted Horror and gave my opponent some 3/3 Centaurs, my opponent controlled those tokens, but since my Hunted Horro created them, I owned the tokens.
Under the new rules, my opponent is concidered the owner of those tokens, which just doesn't make any god damned sense to me at all, but my disgust aEt the rule change doesn't hinge on the logic behind it. No, it pisses me of for more practical reasons than ideological ones.
To put it plainly, the new rule completely hoses one of my favorite decks I ever designed. Here's the decklist:
4 Gilded Drake
4 Hunted Phantasm
4 Hunted Dragon
2 Sky Swallower
3 Echoing Truth
2 Prophetic Bolt
3 Sol Ring
3 Izzet Signet
4 Steam Vents
4 Shivan Reef
3 Izzet Boilerworks
In case it's not immediatly obvious the deck is built around the card Brand, a rare from Urza's Saga that was pretty underwhelming and terrible even BEFORE the M10 rules nerfed it even more. Thanks to the Ravnica "Hunted" cycle I was able to put a whole mess of janky rares to surprisingly great use. Even the non-Simic version of the Sky Swallower got some love here, and rares don't get much worse than that one, folks!
So basically the game plan was to stall early with some bounce, burn and counter. Then when something good hits on the other side of the table, you swap your Gilded Drake for it, and then Brand to get the Drake back on your side. Then you drop a couple Hunted creatures, and use another brand to selfishly hoard all those tokens. So with Hunted Dragon, you get a 6/6 Hastey Flying dragon, AND 6 power worth of Knight tokens for a grand total of 6 mana and an extra card.
In a pinch Echoing Truth can help with those tokens if you don't draw a Brand in time. Bouncing the tokens isn't nearly as fun as stealing them back, but it works, trust me. Another cool interaction is playing out two or three Gilded Drakes, taking the best stuff your opponent plays, then Echoing Truth the Drakes back to hand, so they have nothing and you're ready to just steal even more of their shit. In this scenario the Truth is usually even better than Brand.
In short, the deck was designed to exploit the ownership rules, but now that trick no longer works, and the already-bad Brand is now utterly horrible. And one of the funnest and coolest casual deck I'd ever built is now unplayable. :(
But, that doesn't mean the basic pricipal at work here can't be retooled to fit the new rules, largely thanks to an underplayed and underappreciated Planeswalker: Venser the Sojourner. This guy is far more versatile and abusable than Koth of the Hammer or Tezzeret, Agent of Bolas, but people don't seem to care too much for poor ol' Venser.
One of the first cards that came to mind when I read Venser's first ability was Vedalken Plotter. For three mana, you swap one of your lands for one of your opponent. In a vacuum this doesn't really do a whole lot of good for you, but what if, once you performed the swap, you used Venser to "blink" the land you generously traded away, and at the next End Step, the land came back into play under your control again? That seems pretty good, right? It's like a 3-mana Annex that can't be disenchanted.
Then, you can use Venser to blink the Plotter swapping lands, then the next turn, blink the lands. Sounds cool, but it gives the opponent one turn in which to make use of your land, and that's not cool. Rings of Brighthearth solves that problem nicely!
Another fairly crappy card that seems like it could be fun here is Puca's Mischeif. You probably have no clue what that is. Go ahead and click that link... I'll wait.
So yeah, another swap effect basically, but one that's free each turn after you cast the enchantment. Gilded Drake is another obvious inclusion as one of the few cards that ports over from the Hunted deck without loosing it's appeal. Swap the Drake for anything good, then use venser to blink the Drake again if they dare play another solid creature. It won't get the Drake back on your side permanently, but it's still a pretty effective way to repeatedly Control Magic their dudes.
So with Vedalken Plotter, you can steal their lands, Gilded Drake steels creatures, and Puca's mischeif steals whatever the other two can't target. You can even swap the Puca's Mischeif itself for anything costing 4 or less! You'll actually be happy to see your opponent drop a Jace the Mindsculptor!
Beyond "swap" cards, virtually anything with a good "Eners the Battlefield" ability will play nicely with Venser. Mulldrifter has one of the all-time best ETBF abilities, so a few copies of Drifty McMulls should go in. Aether Adept or Man-O-War can help with early defense, and get better with blink effects.
Wall of Denial doesn't have anything to offer by way of ETBF effects, but it's a solid defense and will help protect your BFF Venser. A quick gatherer search for Blue and White guys with the text "enters the battlefield" will give you a whole slew of options, and you can go a lot of different routes with a deck like this. I just prefer to play a tempo-control game while stealing my opponents resources at the same time.
You could up the ante on land-theft by playing actual Annex. With access to all your opponent's mana, why not help yourself to their hand as well? Muse Vessel would play well here, but it's starting to feel like a totally different deck, and one that might not even want the Venser blink engine.
I'm thinking more along these lines:
4 Vedalken Plotter
4 Wall of Denial
3 Gilded Drake
1 Solemn Simulacrum
2 Glen Elendra Archmage
3 Venser, The Sojourner
1 Puca's Mischeif
1 Rings of Brighhearth
2 Faith's Fetters
1 Momentary Blink
1 Spine of Ish Sah
4 Azorius Signet
4 Sejiri Refuge
4 Glacial Fortress
4 Adarkar Wastes
1 Hamilar Depths
Or something along those lines...