Hi,
I've been playing for a few days, beginning with a sapper, and I wonder how to use barriers.
Are they just an obstacle to the progress of the enemy ?
Do they block bullets, spells ? If yes, do they also block your teams' ?
How to use it well ?
Any help would be much apreciated

It can protect from ice witch. Also it can be used to protect other dwarf's building, for example, steam hammer.

There are many ways to use the barrier.
- Use it to stop gunfire and magic. Anything ranged it can block. Be wary though it will block your own teams shots.
- Use it to block a route. Some routes can be bottle necked pretty easily with the use of a wall if not completely blocked. On the second PoC on Alchemist's citadel you can actually block one set of stairs pretty effectively with it where you can jump down the stairs but not up and over it. Another great use of it is filtering people over certain areas. The steps on Hall of our Fathers is a good example. set up your wall at the top of the stairs and then put traps in the opening. Watched several people run through that hole today and hit 3-4 traps and die.
- Use it to protect things. Place down something valueable in a corner then put the wall in front of it. It'll disguise it and make it harder to kill.

find many different ways to use it. For me on 1-4 its a staple. Its priceless especially vs gunners.

nebylo by špatné dát bariéře že i nepřátelé mohou přeskočit, protože dám hammer zabarikáduju to a každý to přeskočí zničí hammer a barikady tam necha. a to samé i fire sister s fire ball zničí hammer a barikády nechá.