How to make a teleporter (part) with fade effect?

Make a while loop that cycles through all of a character's body parts, increments the transparency of each one slightly, and then waits. Then what you need to do check in the while loop if the transparency of any of the body parts is equal to 1, and if it is, then teleport the player (set the position of the characters HumanRootPart to a vector3 equal to the position you want the player to be teleported to) after the player teleports, have the teleporter keep a reference to the player and slowly decrement the transparency of all their body parts.