Brand is a red spell with which you "Gain control of all permanents you own". What does this actually do? Wouldn't you already have control over your permanents? When would this card be useful? Does this apply to permanents that where exiled or sent to your graveyard?
Magic has this definition for "permanent":
110.1. A permanent is a card or token on the battlefield. A permanent remains on the battlefield indefinitely. A card or token becomes a permanent as it enters the battlefield and it stops being a permanent as it’s moved to another zone by an effect or rule.
So, Brand only cares about cards and tokens currently on the battlefield.
Magic has the following rules about ownership:
108.3. The owner of a card in the game is the player who started the game with it in his or her deck. If a card is brought into the game from outside the game rather than starting in a player’s deck, its owner is the player who brought it into the game. If a card starts the game in the command zone, its owner is the player who put it into the command zone to start the game. Legal ownership of a card in the game is irrelevant to the game rules except for the rules for ante.
110.5a A token is both owned and controlled by the player under whose control it entered the battlefield.
And one about control:
- 110.2. A permanent’s owner is the same as the owner of the card that represents it (unless it’s a token; see rule 110.5a). A permanent’s controller is, by default, the player under whose control it entered the battlefield. Every permanent has a controller.
Basically, the permanents you own are the cards you put in your deck and the tokens you made, and you start out controlling the permanents that you put into play.
Brand allows you to regain control of any permanents you lost control of in any of those ways. For example, you can exchange control of a bunch of permanents you control with permanents your opponent controls, and then cast Brand to get your permanents back.
Contemporary uses could be to combine it with a card like Scrambleverse. After everything gets "Scrambled" you could take back everything that's yours, so you'd end up with whatever you managed to steal from other people plus all your original permanents.
It's also sometimes combined with Zedruu the Greathearted in EDH decks to get back all of the things you've been giving away for a big finish. (e.g., you might give away many enchantments then when you finally get Opalescence in play steal them all back.)
In the past the rule for tokens was that a token's owner was the player who controlled the ability that created the tokens. So you could follow a Hunted Dragon with Brand and steal back the tokens it created. This no longer works after M10.
It would not apply to cards in zones other than the battlefield since by definition a 'Permanent' is a card on the battlefield.