Minecart with Monster Spawner

Minecarts with spawners are a combination of minecarts and spawners.

Obtaining
Minecarts with spawners cannot be obtained as an item in the inventory, and must only be placed using the command.

Usage
The spawner inside the minecart acts the same way as normal spawners; it has the same associated NBT tags.

More exactly, a spawner minecart acts as a spawner block at the minecart's block position. In other words, if the spawner minecart moved within a block position, the range of spawn would not change.

Drops
When they die, spawner minecarts drop 1.

Entity data
Minecarts with spawners have entity data associated with them that contain various properties of the entity.