What can I walk through using Spirit Walk?

Spirit Walk is actually pretty straightfoward after a couple of uses. For the duration of the spell (2-3 seconds) you are able to move through any enemies, and remove all movement impairing effects.

This means:

Slow down effects are removed. You can escape most roots, such as from any Jailer type elites. You can walk through enemies (if you can click a free floor space).

You cannot walk through anything physical however. Any effects which create a game-object "cage" will trap you... ie Diablo's cage spell.

You cannot walk through the walls created by "Waller" elites. You cannot walk through closed doors. You cannot walk through walls.