i did my best to show the easiest way to get through the level and portal walkthrough test chamber 18 (advanced) theportalwiki wiki portal test chamber 18 (advanced) as part of a complete portal puzzle walkthrough for halflife2. i tried to make things look as normal as possible. Sorry i had to do a lot of editing for this one. Portal 1 Test Chamber 18 Advanced Walkthrough (20th Advanced Chamber)
