Teleportation

An effect type. A teleportation power transports creatures or objects instantaneously from one location to another. Typically, a creature teleports by means of a magical power, such as the wizard spell dimension door.
    Unless the description of a power or other effect says otherwise, use the following rules when a creature uses a teleportation power on a target, which might be itself, another creature, or an object.

Instantaneous: Teleportation takes no time. The target disappears and immediately appears in the destination that the teleporting creature chooses. The movement is unhindered by intervening creatures, objects, or terrain.

Destination Space: The destination of the teleportation must be an unoccupied space that is at least the same size as the target. For instance, a Large creature cannot be teleported into a space that is only 1 square wide.
    If arriving in the destination space would cause the target to fall or if that space is hindering terrain, the target can immediately make a saving throw. On a save, the teleportation is negated. Otherwise, the target arrives in the destination space.
    If a prone creature teleports, it arrives in the destination space still prone.

Line of Sight: The user of the teleportation power must have line of sight to the destination space.

No Line of Effect Required: Neither the user of the teleportation power nor the target needs line of effect to the destination space.

No Opportunity Actions Triggered: When a target teleports, it doesn’t provoke opportunity actions, such as opportunity attacks, that are triggered by movement.

Immobilized or Restrained: Being immobilized or restrained doesn’t prevent a target from teleporting. If a target teleports away from a physical restraint, a monster’s grasp, or some other immobilizing effect that is located in a specific space, the target is no longer immobilized or restrained. Otherwise, the target teleports but is still immobilized or restrained when it reaches the destination space.

Not Forced Movement: Teleporting a creature, even an unwilling one, does not count as forced movement.

Published in Player's Handbook 3, page(s) 218, Monster Manual 2, page(s) 219, Player's Handbook, page(s) 286, Monster Manual, page(s) 283, Player's Handbook 2, page(s) 221, Rules Compendium, page(s) 213-214, 316-317, Monster Vault: Threats to the Nentir Vale, page(s) 125.