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|02]-portal invariant

In the next test, Aperture Science notes the possible discouragement of test subject [test subject name here] while reminding that the cool breeze from excursion funnel is completely safe in most cases and hopefully will uplift test subject's spirit. But you know the old formula: what goes up, must come down and you do have a weight of testing on your shoulders.

Difficulty: medium/hard.

Hints to obscurity:
To get upper ledge after getting cube, fizzler and laser field need to be reversed first.
You can't take portal device outside of designated testing areas, but you can take cube to bottom floor without it fizzling.