So, when I the Soul Cairn, there are these pillars a bit taller than you with holes at the top. There are ones next to barred gates with orbs in them that seem to be the unlocking mechanism for the gates. I unlocked one gate by casting firebolt on them and the orbs faded away. But that doesn't work on the other pillars that I've found. Any idea what to do with these?

I used the crossbow to hit them, that always worked for me.

Fus works on the ones I find every time.

Neither of these work for me. The bolt just goes right through and Fus does nothing.

The orb stayed there after I hit it. Maybe you've already hit it?

That was it. Thanks

I was confused by the fact that it faded the first time I did it. Had to do some searching for the other pillar too.

No problem. I was confused at first too.