Captain's Mode

As I have never played CM, I would like to know some common bans and pick and reasons why so to help me start playing that mode :) Can some1 help me?

Just search some Hero Tier lists, anything ranked S are the priority first two bans, after that its all about countering or creating a better line-up then the opposing team.

Simply telling you the common picks/bans is hard because every hero patch the meta shifts and there are different priority line-ups, being good at captain's mode is an art, and takes time and research. Start with watching professional and broadcasted gameplay.

Common Bans :

Keeper of the Light - Lane destroyer, anti pusher, great AOE damage, free mana, free teleport, AOE blind and really fast farmer, fast Mekansm or Pipe of Insight
Undying - Lane destroyer, team fight destroyer, durable
Nyx Assassin - Great burst, takes down squishy heroes like supports in a combo, hard to kill and burns your mana
Batrider - Good mid laner, great initiator, can disable through Black King Bar
Dark Seer - Awesome solo laner and an outstanding team fight manipulator
Magnus - Instant AOE stun that goes through Black King Bar, can farm safely, can escape and can boost the carry's damage and give him free cleave

And so on...

Common Picks:

All heroes mentioned above +

Chaos Knight + Io - Really good combo, also easy to use
Bane - Can disable multiple heroes for a long time
Shadow Demon - Amplifies damage, a slow that goes through Black King Bar and can disable enemies + make them kill themselves with illusions
Lifestealer - High damage, hard to kill, free Black King Bar, good slow that gives everyone life steal
Lone Druid - One of the best hard carries and farmers, can get Radiance really fast in order to use it's effectiveness at max level early game
Nature's Prophet - Can push and farm really well, can be anywhere really fast, good ganker, can back door and take down lanes by himself

And many more, looking at professional matches will help you a lot! :)

Ty for help guys, btw. why Chaos Knight and Io is good combo?

Very hard to escape from, and Wisp gives CK that extra attack speed he needs. Essentially its a 3 disable combo that you can use Wisp's teleport to gank whoever you want, whenever.

Also, since CK picks up Drum, its so easy to hit that stun with Wisp's Tether.

Because they are very mobile and Io can boost Chaos Knight's power. Also, he can save him.

Io can keep Chaos Knight full mana so he can use his stun as much as possible in order to get kills. Also, while Io is Tethered to Chaos Knight, if he Reality Rift's, the enemy hero will be inside the link, furthermore he will be stunned and Chaos Knight can get an easy kill.

Io also can teleport him anywhere on the map, in order to gank as much as possible, get many kills, gold and experience.

He can make sure Chaos Knight is farming and getting the items he needs.

Also, since Chaos Knight lacks attack speed, he can use Overcharge to fix that.

We can say, Io completes Chaos Knight.

You can also say that xCO2 completes Hades . No ****.

Yeah, you're my Io <3

But I hate Wisp... :(

I think CO2 is your CK. <3