Encased Smoker is a new block from the Twilight Forest mod. It is used to send out smoke.
To use the Encased Smoker, simply place the jet on the ground and apply a redstone current. The jet will not turn on for a few moments, then will emit a large jet of smoke. It will then shut off, and you need to reset your redstone input to run it again (turn off power; turn it back on). You can use a redstone current loop to power it to constantly keep the device on.