Moodle wants you to collect 10 Lifeblood Shards, but stay away from the cave inside of the pillar itself. If you lose Moodle's Stress Ball, speak to High-Oracle Soo-say in Rainspeaker Canopy.
I've always suspected that the pillars have been the main reason for our weather and seclusion from the undead... this confirms it a bit.
Not terribly long ago, there was a sound of a great explosion when the Lifeblood Pillar fell. The weather changed for the mosswalkers almost immediately... it began to snow, something we never see.
They were able to stop the snow by bringing more lifeblood crystals to the Great Moss Stone. Perhaps if we can do the same, it will help ward off the undead as well.