I've bought one box of Forgotten Relics with a friend of mine,these cards are legal for play?Do i have to buy the core set to be legal?

Its worth buying the starter to get the rules and a good mix of base cards. You can still use the cards you've bought of course, but it will be easier if you have what the starter gives you.

Short answer: no one knows just yet.

Long answer: You will need some sort of starter to get the story cards to use for official play. Here's where it gets fuzzy. A few of us were told at GenCon by Nate that after enough AP packs come out, the game is going to white border cards only for official tournaments. So that's core set and most of the AP packs (anyone got the names & numbers for white border?) There has been an uproar over no support for black border cards, so FFG may change their mind and do some black border/classic/vintage tournaments, but I can't imagine them getting as much support as the white. No one even knows if you will need the Core Set story cards for black border/classic/vintage tournaments if they happen.

Best thing to do is practice with what you have and wait for more info on the tournament scene to be released.

At the very least you need some story cards one of the starters.

It depends on where you are going to play.

Home: well no one makes rules at home, except the rules that you and your guests agree on.

Casual play at a Game Store: If you can get your opponents to play with you, they could play against you with Black border cards, White border cards, or a mix. If you all agree.

Upcoming League at a Game Store: They are very clear that you have a limited card pool and they are all white bordered. You actually must have a core set, or you won't have enough legal cards to make a deck.

Tournament Play at a convention: That's the one that people are waiting for rules that specify if it will be White-only, B&W, or perhaps multiple tourney tracks that allow both Classic and New play.

When you use the word "Illegal", I'm assuming you mean some sort of Sanctioned Play. But that's only just starting with the League that begins in March.

I'm assuming that you did not mean municpal, state and federal laws, which are mute on what card games you can play in your home and which you can't.

Actually, it's hard to image someone would want to try Sanctioned Play with only a few black-border starters. But the game would play just fine at home in that fashion, assuming you had all the story cards.

I have also bought 3 starter decks,i forgot to mention.So for the tournaments i need only the white bordered cards...I think that this is the way of the company to revise the cards for errors and uber cards.I live in Greece and i don't have players here to play except of one friend...The game is more strategic than the current form of Magic:The Gathering and it is more fun!