Red:
appears on desk in room with 3 large pressure plates, 4th hidden, requires helmet.

Blue:
in large room with beds everywhere, wear helmet to walk into walled-off room to pull lever that spawns platforms up to orb high on wall.

Purple:
middle of academy, wear helmet and follow new ramp

Green:
in cage above broken floor/runes, wear helmet and jump platforms, always land on solid platforms that are always there when removing/putting on helmet, or platforms will vanish under your feet.

White:
appears on alter in hallway, solve colored torch puzzle along the hall leading to alter, equip helmet to see phantom torches next to real torches, match phantom torches to color of real torches.

I placed all the orbs on all the runes according to the clues, but nothing happened! What now?
Read all clues carefully.

Still don't know?
Most common mistake is mis-reading the clue about the mossrat

still dunno, spell it out for me.
[spoiler]The clue states mossrat goes on opposite of life, the opposite of life, is death.
[/spoiler]