Captain mode consists of a banning phase and a picking phase - this is called drafting. Each team has 4 bans and 5 picks. The drafting is using this format:
Bans: 1-1-1-1-1-1-1-1 (8 heroes in total)
Picks: 1-2-2-2-2-1 (10 in total)
One team has firstpick and the other team has lastpick. Being firstpick gives the advantage of getting the possible best hero in the hero pool - yet having lastpick gives you the possibility to pick 1 hero that completely counters the opponents team.
In 59d bloodstone was extremely strong and therefore a few heroes got a status of freewin: Krobelus, Necrolyte, Dirge, Rhasta, (Spectre as always).
With firstpick it was possible to get one of these if somehow 4 of them were banned.
A more general example is firstpicking a pusher strat and the opponents lastpick pitlord, also known as the turtler nr. 1.
This is the very basic idea and I will gradually raise the level of insight into drafting as you read on.
Ks^Puppey.ee: "Too noob to play it, hate it, imbalanced, MiseRy loves the cock and so on. But mostly banning for strategic reasons"
Whenever you ban a hero, the hero gets removed from the pool for both you and your opponent. The only reason why you ban heroes is because you don't want to play against them, however I will name a few reasons to why you don't want to play against them.
If you feel a personal hate to a certain hero, an example could be witch doctor, then feel free to ban this hero. If you hate a hero, it's often because it 'counters' your playstyle. Just because other teams have no problems with Troll, doesn't mean that you are not allowed to ban it. Don't act pro, do what you want and learn from your mistakes.
In most versions, there exists a selection of few heroes which are considered to be overpowered. If you don't count on picking them, it's better to have them banned.
3)Knowing your opponent:
In most inhouses or tournaments, you know your opponent and which heroes they prefer to play. Banning a couple of their favourite heroes is often a really safe and succesfull way of banning.
When picking heroes there are alot to consider. You must know that as a general rule every lineup has a counter and that a certain hero is most efficient with a certain playstyle. Just like the item build on a specific hero can change and is not set in stone, so is the role on every hero changeable. Who knows if a support storm with gem might be invented in some unusual lineup. Viable or not, it is how you play the heroes you pick, that defines the winner and the loser.
Everytime you draft and lose or win, you must consider what went wrong and right, and what could have failed or where you got lucky. This way you teach yourself the connection between picking heroes and playing them.