Obstacles are trees, logs and rocks that are randomly placed in your village. You start with about 40 obstacles around your village. You can remove them if you have an available Builder and a small amount of Gold or Elixir. Gold is used to remove rocks and Elixir to remove vegetation.
Stone (Small 1)
Stone (Small 2)
Stone (Small 3)
Stone (Small 4)
Halloween Decorated Obstacles
Halloween Mushroom (2012)
Halloween Mushroom (2013-Present)
Halloween Trunk (1)
Halloween Trunk (2)
Halloween Trunk (Fallen)
Halloween Tree (Medium)
Halloween Tree (Large)
Halloween Headstone (2014)
Halloween Cauldron (2015)
Scary Pumpkin (2016)
Winter Decorated Obstacles
Winter Trunk (1)
Winter Trunk (2)
Winter Trunk (Fallen)
Winter Tree (Small)
Winter Tree (Medium)
Winter Tree (Large 2012)
Winter Tree (Large 2013)
X-Mas Tree (2012)
X-Mas Tree (2013)
X-Mas Tree (2014)
X-Mas Tree (2015)
X-Mas Tree (2016)
Builder Base Obstacles
Tall Grass (1)
Tall Grass (2)
Stone (Small 1)
Stone (Small 2)
Old Barbarian Statue
Each obstacle that is removed can contain anywhere from 0 to 6 Gems.
There are three cycles governing the amount of Gems you receive by removing obstacles in your Home Village and Builder Base. All three cycles are identical to each other, occur concurrently and are independent of each other, meaning that clearing an obstacle advances only one of the below cycles and has no effect on the position of the other two cycles. These cycles repeat as follows: 6, 0, 4, 5, 1, 3, 2, 0, 0, 5, 1, 0, 3, 4, 0, 0, 5, 0, 1, 0.
The first cycle governs the amount of Gems you receive from an obstacle in your Home Village. It advances when you remove an obstacle in the Home Village.
The second cycle governs the amount of Gems you receive from the original obstacles in the Builder Base (i.e. the obstacles that are spawned when you first enter the Builder Base). It advances when you remove such an obstacle in the Builder Base.
The third cycle governs the amount of Gems you receive from spawned obstacles in the Builder Base (i.e. obstacles that spawned sometime after you enter the Builder Base). It advances when you remove such an obstacle in the Builder Base, but it resets every time a new obstacle spawns in the Builder Base.
You can take advantage of the third cycle since the first removal of an obstacle after the cycle resets always yields 6 Gems. Simply wait for an obstacle to respawn in your Builder Base and then remove exactly one obstacle to yield 6 Gems from every respawned obstacle in the Builder Base.
Even if you do not get 6 Gems by using this technique (you may have removed one of the original obstacles) you can continue removing obstacles until you get 6 Gems (ensuring you remove one of the respawned obstacles), since the earlier removal of obstacles advance the second cycle and not the third cycle.
On average, each obstacle cleared has 2 Gems. This pattern does not include the 25 gems held from the Gem Box, or the holiday themed Obstacles like the various Halloween Obstacles (2014~2016) which have Elixir; the X-Mas Trees (2012~2016) have Gold instead.
Vegetation respawns at a rate of one item per eight hours, except if all the spaces in your village are totally filled. Furthermore, an obstacle will only spawn if there is a 1-tile buffer zone between the spaces in which it will spawn and another building or obstacle.
Rocks do not respawn once they are removed.
You can't place buildings on obstacles.
Since vegetation respawns, and removing one may have Gems, removing vegetation regularly can be an unlimited (although slow) source of Gems.
If you accidentally set a Builder to remove an obstacle it is possible to cancel if tapped before the Builder is finished.
Cancelling the removal of an obstacle will refund you 100% of the resources spent. Cancelling an upgrade returns only half of the resource cost.
Your village can have a maximum of 44 obstacles at one time. This doesn't include holiday themed obstacles.
When the Gem Box was added it was quickly deleted due to a few glitches relating to how many Gems it gives. The Gem Box was added back into the game on April 9, 2014, the update that added Clan Wars.
You can only have 1 gem box at any time in a village. Clearing the Gem Box costs 1,000 Elixir. It takes 30 seconds to clear one, and the removal of one will have 25 gems. The gem box is rare, but in the April 2014 update their spawn rate was increased.
Note that all special obstacles (and the Gem Box) ignore the one-tile buffer zone rule that governs where normal vegetation can spawn. They can spawn in any 2x2 empty space within your village, though they tend toward spawning close to the outer edges of the field.
During the Winter 2012 Update, they added a X-Mas Tree that gives 30,000 Gold when cleared, which was then increased to 50,000. On 3 January 2013, Supercell indicated on the forums that people will get to keep their trees even after the winter theme is gone. The 2012 X-Mas Tree appears as a small tree with flashing colorful ornaments.
There's a 2012 edition of X-Mas Tree in the far left edge of the map in Gold Rush mission in Single Player Campaign in the line of trees that are surrounding the map, 2013 edition of X-Mas Tree in Gobbotown mission and the 2014 edition of X-Mas Tree in Fool's Gold mission.
During the Winter 2013 Update, they introduced another X-Mas Tree that gives 75,000 Gold when cleared. The 2013 X-Mas Tree appears as a small tree with golden garlands, a golden spike ball on top, and two skulls at the bottom of the tree.
During the Winter 2014 Update, Supercell introduced an X-Mas tree that not only gives 75,000 Gold when cleared, but randomly spawns wrapped presents worth 5,000 Elixir each when cleared. The 2014 tree is similar looking to the 2012 one, but is adorned with tinsel, candy canes as well as colored ornaments and flashing lights.
During the Winter 2015 Update, they introduced an X-Mas tree that gives 75 000 Gold after cleared. This tree appears like black metal tree with golden chains, spikes and spiky ball on top. There also lays sword next to it. When zoomed, you can see sparks coming out.
During the Winter 2016 Update, they introduced an X-Mas tree that gives 75 000 Gold after cleared. This tree has red ribbons.
There's a special kind of Army Camp in the Goblin Gauntlet mission in the Single Player Campaign that only consists of a camp fire with different surroundings that the one in the Army Camp, which is only 2x2. You can notice this by the other obstacles that are next to the camp fire. You can also drop troops over it since it is considered as an obstacle.
Video of X-Mas Tree (2012) being chopped down and the reward: Video
The Tall Grass is the only Builder Base Obstacle that doesn't require a free Master Builder to remove, and will never yield Gems. You can either remove it with 50 or for free by placing a building on it.
The Old Barbarian Statue will spawn Tall Grasses by its side. The same goes for the Ancient Barbarian Statue decoration.
The rainbow effect on the Gem Box might be a reference to the saying "There's a pot of gold at the end of the rainbow." However, in this case, the pot of gold is a pot of gems.
If no gems are purchased, earned through achievements or spent on various purposes, 1623 obstacles (not including gem boxes) are needed to clear to buy the 3rd, 4th and 5th builder huts which cost 3500 gems in total, which roughly translates to 528 days (counting from the first obstacle removed and assuming that the village always contain less than 44 obstacles, in order for new obstacles to spawn).
In very early versions of the game, an odd looking stone was able to appear in your village. It was removed quickly and right now only 1 player is known to have it (Player tag: #QJRGU0).