“Troop building that periodically deploys Skeletons to fight the enemy... and when destroyed, spawns 3 Skeletons! Creepy.”
The Tombstone card is unlocked from the Bone Pit (Arena 2). It is a building that spawns one Skeleton every 3.1 seconds. The Tombstone spawns 3 extra Skeletons upon its destruction. A Tombstone card costs 3 Elixir to deploy.
The spawned Skeletons are very effective at distracting high damage, slow hit speed enemy units such as the P.E.K.K.A., the Prince, the Mini P.E.K.K.A., and the Giant Skeleton. This is especially effective against units that target buildings, such as the Giant and Golem — the Skeletons spawned after the Tombstone's destruction can heavily damage, if not completely destroy, the unit.
In the case of the Golem, the Golem's death damage may defeat the Skeletons and the Golemites may deal some damage to the tower.
It can also distract other units for a while, such as the Princess or Mortar.
If any other ranged troop is locked onto a Tower, the player can use the Tombstone to push the troop so it retargets on to the Tombstone. This cannot be done with any defensive building as they do not have a large enough hitbox to push the troops, but the Tombstone works because the spawned Skeletons have enough hitbox space to push the troops. The Skeletons will then chip away at the troop's health.
As a general rule of thumb, all buildings except for the Elixir Collector should be placed near the center of the player's territory so that enemy troops are drawn further away from the player's Princess Towers, while keeping them close enough so that both Princess Towers can assist in chipping down the troops. A placement 4 tiles from the river staggered into the lane of the player's weaker Princess Tower is sufficient against building targeting troops.
If the opponent plays their Hog Rider at the edge of the arena to bypass the player's Tombstone, they can place the Tombstone one tile higher to catch it every time. However, this makes the Tombstone much more vulnerable to being sniped by ranged units across the river.
The Tombstone can spawn up to 15 Skeletons, 12 of which are spawned normally over the lifetime of the Tombstone. It then spawns 3 more when it is destroyed. A Skeleton Army costs the same amount of Elixir and also spawns 15 Skeletons, but a Tombstone is not as vulnerable to splash units or spells as the Tombstone's Skeletons spawn periodically as opposed to all at once.
The Tombstone is rather ineffective against Bowlers and Executioners, since their projectiles have the ability to not only destroy the building but also to destroy the recently spawned Skeletons.
Do not place this card in a lane offensively without any support since the Skeletons it spawns get destroyed by Crown Towers in one shot and do not function well as cover troops.
The Log can be an excellent counter to the Tombstone. If timed correctly, it can not only destroy the Tombstone but also destroy the Skeletons that spawn upon its destruction.
If the player does not have The Log, Arrows work as a good substitute as they do roughly the same damage. However, it is more expensive and it is harder to time them to destroy the Skeletons spawned upon the Tombstone's destruction.
Another alternative to The Log is the Fireball which can instantly destroy the Tombstone. However, this is a negative Elixir trade of 1 unless other troops or buildings are also damaged. The Fireball will also not destroy the Skeletons that are spawned upon its destruction.
The Tombstone card was added with Clash Royale's soft launch on 4/1/16.