Drop-C Tuning, I think.
This is just the heavy part. I'll work on the other parts soon.
[ Tab from: http://www.guitaretab.com/i/isis/85380.html ]
|-------------------------------------------------------|
|-------------------------------------------------------|
|-------------------------------------------------------|
|-0-h10-h12-0-h10-h12-0-h10-h12-0-h10-h12-/15-15-15-15--|
|-0-h10-h12-0-h10-h12-0-h10-h12-0-h10-h12-/15-15-15-15--|
|-0-h10-h12-0-h10-h12-0-h10-h12-0-h10-h12-/15-15-15-15--|
|--------------------------------------------------|
|--------------------------------------------------|
|--------------------------------------------------|
|-0-h10-h12-0-h10-h12-0-h10-h12-0-h10-h12-3-3-3-3--|
|-0-h10-h12-0-h10-h12-0-h10-h12-0-h10-h12-3-3-3-3--|
|-0-h10-h12-0-h10-h12-0-h10-h12-0-h10-h12-3-3-3-3--|