I have played many mmorpgs and in one of those there was an event that was highly rewarded, but limited as well and I would love to see it here.

We know how big the role of crystals and the visions in the main story we see the main character floating and the crystal talking to him/her. We have also seen where in the cinematic each one class goes and pray to the crystal pieces.

Here's my suggestion:

How about adding a event that is available once every year and the quest is a worship or celebration to the crystals. Where you start the quest talking to a random NPC and has a small story to tell, but while he is telling the story he also ask you for favors such as hunting enemies, getting a drop from a designated mob, crafting materials and killing mini bosses. Has to be a long chain quest that would take you a few hours to do it and travel to different locations.