To do it the way you tried, you must change back to room 5 from the "enter room" function of room 100 (since you cannot invoke two changeroom requests in a row, they are only processed after the current script is finished).
However, Strazer's way is better. Additionally, you can make a character invisible by either setting them to a loop/frame that is blank, setting their X or Y coordinate to something ludicrous, or setting their transparency to 100%
However, Strazer's way is better. Additionally, you can make a character invisible by either setting them to a loop/frame that is blank, setting their X or Y coordinate to something ludicrous, or setting their transparency to 100%