I just see people mentioning constructed, 'I play constructed' for example. So in Arena you don't own any of the cards but can pick from all of them to build a deck?
Yeah sorry I should have been more specific earlier.
"Constructed" is a term from another Card game called "Magic: The Gathering". It means a format in which you choose your own cards to put in your deck from your collection - in Hearthstone terms it is the equivalent of "Play" mode.
You are half correct about Arena, you can pick cards that you don't own, but there is a big, big, catch!
In Arena:
1. You are initially presented with a choice of 3 random heroes, and need to choose one of them. So here there is a risk you could be stuck with a hero you aren't familiar with, or even like.
2. You are then shown 3 cards randomly picked from all neutral cards and all cards from your chosen hero card pool. You can only pick one of them.
3. Step #2 is repeated 30 times until you have enough cards for a deck.
4. You then pit your deck against other players who have been through the same process, and see how you go!!!
Some interesting things about arena:
- Since the cards you are presented with each time are random, it is possible to have more than two cards of each type in your deck. For example, over the weekend, I drafted a Mage deck with 5 (yes, 5!!) Fireball spells.
- Sometimes you get three bad choices, and have to pick a poor card. Its bad luck, but it happens.
- Sometimes you have to skip over really good cards because (for example) you are up to your 25th card and have no removal, or heavy hitters, etc.
Its quite fun and each Arena playthrough is unique. You are playing against others that are playing with sub-optimal cards too so you never know what is going to happen each game.