Barbarians wield long swords and have blond hair and amazing mustaches.
The Barbarians are a great option to use against enemy cards and Crown Towers, as the spawned troops have a moderate amount of hitpoints and damage, and are perfect for attacks with other tanks. They are not effective at tanking unless your opponent has no splash attackers or spells that can destroy all the Barbarians.
They are excellent for taking out low numbers of enemy troops such as the Prince or Musketeer on the player's side. The 4 Barbarians will quickly eliminate the target if they are dropped directly on top of it and surround the unit.
A successful defense with Barbarians will also make for a powerful counterpush if the Barbarians are protected from splash troops.
They can also defeat a splash unit if placed correctly, but failing to surround the splasher with Barbarians will cause them to take more damage than necessary.
The Barbarians can be effectively countered by most splash troops such as the Bomber and Valkyrie. However, be sure to plant them to the side so they are not immediately mauled. However, you must be careful as the opponent can use a Tornado or Freeze to immobilize or destroy the splash attacker, and the Barbarians can devastate the Crown Tower. Fire Spirits can do severe damage to the Barbarians, and are also very cost effective. Note that Fire Spirits alone will usually be unable to completely eliminate an entire group of Barbarians. Finish the Barbarians off with other troops or allow the Crown Towers to finish them off.
A powerful counter is the Fireball; the damage and radius of the spell is more than enough to severely wound all the barbarians such that they can be one-shotted by the Arena Tower. Afterwards, if the Barbarians' health is lowered, the player can easily finish them off.
Poison can also be an effective counter to use. Its Damage over time will eliminate, or deal high damage to, the Barbarians and any supporting troops. However, the Barbarians will eventually walk out of the Poison with a fair amount of health left.
If the Barbarians survive, try supporting them with a tank in front to get some use out of them.
Rage used with Barbarians can do severe damage to a Crown Tower, as it is hard to stop because Rage increases movement and attack speed. The Barbarians have high damage and can make short work of a tower before the opponent stops them.
Deploying Barbarians down the lane is futile and is essentially a waste of five Elixir unless the opponent is short on Elixir simply because of the numerous counters to the Barbarians. Always be ready to deploy a support troop along with the Barbarians, such as a tank or spell, so that they stay alive for as long as can be kept.
It is a very bad idea to leave them ignored as they will be able to destroy the Crown Tower by themselves.
They are the best troops to take out enemy tanks due to their numbers (4 of them), moderate damage, and tankiness. Support troops will have trouble killing them due to their hitpoints. If the combo happens to be any ground-based splash damage card + ground-based melee tank, wait for the troops to cross the river. As soon as they cross, immediately drop the Barbarians upon the splash card. They will surround and destroy the troop quickly, leaving other troops or themselves free to wreak havoc. This will result in at minimum (Hog Rider + Fire Spirits) a 1 Elixir advantage or at maximum a (Golem + Wizard/Witch) 8 Elixir advantage.
The Barbarians card was released with Clash Royale's soft launch on 4/1/16.
From the Knight's description, Barbarians are said to be distant cousins, due to their physical similarities, especially their awesome mustaches. However, in the card image, Barbarians have blue eyes, while the Knight has brown eyes.