Marshall
First Post
It's a free action that can't be taken on anyone's turn but your own, and not during a surprise round, and only once during an encounter.
The DM can limit free actions though, but the falling excuse isn't supported by the RAW.
RAW doesnt support the "teleport into the air to attack a flying creature" to begin with. The DM was using the "rule of cool" to start with and just stopped the OP from taking the mile after the inch.