The spawned Skeletons are very good 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 which target buildings, such as the Giant and Golem — the Skeletons spawned after the Tombstone's destruction can heavily damage if not destroy the unit.
It can also distract other units for a while, such as the Princess or Mortar.
If a Royal Giant is locked on a tower, the player can use the Tombstone to push the Royal Giant so it switches to the Tombstone. This cannot be done with any defensive building as they don't have a large enough hitbox to push the Royal Giant but works with the Tombstone because the spawned Skeletons have enough hitbox space to push the Royal Giant.
For more effectiveness, the Tombstone can be placed near the center of the player's territory so that the troops are drawn further away from the Crown Tower. They will be distracted by the Skeletons and be unable to target the Crown Tower. Also, both of the Crown Towers will be able to attack the troops. The defending Towers, in collaboration with the Tombstone, can defeat them quickly.
The Tombstone can spawn up to 18 Skeletons, of which 14 are spawned normally over the lifetime of the Tombstone, and then 4 more when it is destroyed. This would cost at least 4 Elixir. Considering that a Skeleton Army costing 3 Elixir spawns 15 Skeletons in total, playing a Tombstone would profit 3 Skeletons, but note that they don't spawn all at once!
Do not place this card in a lane offensively without any support since the Skeletons it spawns get destroyed by Crown Towers with 1 shot and do not function well as cover troops.
An easy counter to this card is the Fireball which can instantly or almost instantly destroy the Tombstone. However, this is a negative Elixir trade unless other troops or buildings are also damaged.
The Tombstone card was added with Clash Royale's soft launch on 4/1/16.