The ectophial is a reward for completing the Ghosts Ahoy quest. Players can empty it, causing them to be teleported to the Ectofuntus outside Port Phasmatys. Once the player teleports, he/she will automatically refill it if you do not interrupt the action by clicking elsewhere. Make sure your Ectophial has been filled before leaving.
It is widely used in fights to escape because it is easy to replace, costs nothing, and is a one click teleport from your inventory. It also only takes up one space, as opposed to Rune-based teleports, which take up at least two. It is also a popular method of transportation when using fairy rings, as it is just northeast of fairy ring alq.
Like most teleport items, the Ectophial does not work past level 20 Wilderness.