As the description says, the Goblin Barrel can be launched anywhere, allowing players to attack or finish off buildings they cannot reach. However, it is easily countered with spells and area damage troops due to their low hitpoints.
If left ignored, the Goblin Barrel will do significantly more damage to a Crown Tower than an equivalent level Rocket for less Elixir. At tournament standard, the Goblins will stab a Crown Tower seven times, dealing 693 damage. If the Goblin Barrel is placed at the centre of a Princess Tower, it will cause the spawned Goblins to split apart on all sides of the tower, making them harder for splash units to defeat.
When a Goblin Barrel is placed in the center of a Crown Tower, the Goblins spawn clumped together and are quickly shoved outwards. This is why splash units will sometimes hit all three Goblins before they are separated, such as a preemptively placed Valkyrie.
The Goblins from the Goblin Barrel have high damage per second, but relatively low hitpoints. If it is being tanked by a high hitpoint troop that distracts the Crown Tower and any defending units, the Goblin Barrel can deal extremely high damage in a relatively short amount of time.
As Goblins have relatively low hitpoints, they can be eliminated fairly quickly by Crown Towers. When using a Goblin Barrel to attack a King's Tower, the remaining towers should be distracted with another unit, lest the Goblins be defeated quickly.
The Goblin Barrel can force the opponent to use their spells, allowing the player to swarm their opponent with cards such as the Skeleton Army and Minion Horde. However, this strategy can backfire if the opponent has some splash damage troops, another splash spell, or a Mirror. If the player has a Mirror, they can send a higher level Goblin Barrel at the tower again, forcing them to react with less effective counters.
When countering the Goblin Barrel, the player must not overreact and play a high cost card unless they are confident that they can turn said card into a counterpush, since the Goblin Barrel only costs 3 Elixir.
Spells like Rocket and Lightning are impractical to use against a Goblin Barrel since it is both a negative elixir trade and may not hit all of the Goblins. However, if the defending player is ahead in a match and their tower is at low health, they can use these spells to clear out a barrel in the final seconds of a match.
Some spells such as Zap and Poison won't instantly defeat the Goblins, so a Princess Tower will take some damage. This is significant enough to fully destroy it over the course of a match if this is the only card played to counter the barrel. The Royal Delivery, Barbarian Barrel, and The Log fully defeat the Goblin Barrel for a good trade.
The opponent may launch the Barrel past, to the side or just in front of the player's Tower, meaning the player may miss with their spells. This is often referred to as a "tricky" or "juke" Goblin Barrel. The player should stay vigilant and pay close attention to the Barrel's shadow and trajectory when mid-air and react accordingly.
A Zap 1 level higher than the Barrel will instantly defeat them.
The Log is the best counter to the Goblin Barrel. A level 9 The Log will defeat Goblins at all levels except 13 and 14 (from a max Mirror), meaning that The Log is a reliable counter in tournament standards and on ladder.
Arrows are a very reliable counter to the Goblin Barrel because of its large area of effect, and level 9 Arrows can all defeat Goblins from the barrel except when they are level 13 and 14. In the rare case that the Goblins do not die to the Arrows, it is easy to level them up to compensate.
A Tornado placed 2 tiles to the left/right (depending on where the Goblin Barrel is flying towards) of the middle of the King's Tower, 1 second before the Goblin Barrel lands will not only prevent all damage from the Goblins, it will also activate the King's Tower.
A Fireball will get the job done no matter what level the Goblins are, but it is a negative Elixir trade. If nothing else can be played to defeat a Goblin Barrel, or it needs to be destroyed urgently, use it anyway because the Goblins' damage potential is too high to ignore.
If the player has no spells, then swarms such as the Skeleton Army and Goblin Gang will be able to negate the damage. When played behind the Princess Tower, both will cover all positions except the front tiles. Fire Spirits are another great counter, although they need to be played earlier then the previous two for the best results. However, be wary of spells such as Zap as they can easily clear these troops out.
A Valkyrie placed one tile up from the bottom-outer corner of a Princess Tower can catch two Goblins in her swing and only let the Goblins get one stab on the tower. The Valkyrie can be placed slightly ahead of time and hit all three Goblins due to her very quick first attack speed.
Good outcomes can be achieved with troops that can 1-shot Goblins; such as the Lumberjack. These counters are somewhat situational and depends on what else the player has to counter Goblin Barrels because the opponent can throw their Goblin Barrels anywhere they please.
Ranged units aren't affected by placement since as long as all three Goblins are in range, the result will still be the same. Archers, Musketeer, Wizard and other ranged units prevent all but two stabs on the player's Princess Tower, and a Dart Goblin only lets three stabs on the tower.
In some situations, the player may want to have the ranged troop tank a few shots from the Goblins in order to prevent more chip damage.
Placing a Bowler behind a Princess Tower will take out all three Goblins with the right timing. The Bowler should finish its deployment timer just as the Goblins spawn. Just like The Log and Arrows, a tournament standard Bowler can defeat all but level 13 and 14 Goblins. Release him once the Goblin Barrel's shadow passes the enemy's Princess Tower. If the opponent tries to mix up their placement, the Bowler will still crush the Goblins anyway. He can then be used to build a counter-push.
This can also be done with Hunter, but does not work if the opponent mixes up their placement.
Due to a similar attack mechanic and counter-push potential, the Executioner can substitute the Bowler. He can destroy two Goblins in one throw, and the Barrel will get two stabs on a Princess Tower.
There is a precise technique for the Electro Wizard's spawn damage to hit all three Goblins. The Electro Wizard should be deployed right when the Goblin Barrel's shadow crosses the river and the Goblins will get a maximum of one stab on the tower. For this to work, the Electro Wizard must be placed directly on one of the sides of a Princess Tower.
This can also be done with the Mega Knight, and will instantly defeat the Goblins, although he costs more Elixir, and it may be more effective to save his damage output for other situations.
The Goblin Barrel was added with Clash Royale's soft launch on 4/1/16.
On 11/1/16, a Balance Update decreased the spawned Goblins level by 1. Prior to the balance, a max level Goblin Barrel could spawn level 14 Goblins, which was 2 levels higher than the max level at the time.
On 19/2/16, a Balance Update decreased the Goblin Barrel's Crown Tower impact damage by 20%.
On 21/6/16, a Balance Update decreased the Goblin spawn time to 1 sec (from 1.2 sec).
On 4/7/16, the Tournaments Update decreased the Goblin Barrel's Elixir cost to 3 (from 4), increased its Goblin spawn time to 1.2 sec (from 1 sec) and removed its impact damage.
Before the May 2016 Update, the Goblin Barrel was able to summon level 13 Goblins while the maximum level for the Goblins card was 12. The Witch was able to do the same with her Skeletons.