Start as mentioned on Illumination Rock main page. From Illumination Saddle, traverse Zigzag Glacier just South of Illuminaion Rock. Climb into the gully separting the W Ridge and SW ridge. So far, just basic glacier travel (little threat of crevasses).
From the gully, climb onto the SW Ridge. From here it is several pitches of AI3 through AI4. See photo. All rime ice. Good belays, alot of exposure.
You'll need pickets and screws. Two tools recommended. Two ropes for long rapelles on descent would be helpful, possibly a light rock rack if you want to descend directly into Ill. Saddle or South off cliff. Otherwise use ice bollards to rapel into gully.
Here are a couple trip reports:
Summer climb on the SW Ridge
A winter climb