Years of neglect on a seal was a simple reason that they might fail. This was why the party had been able to get past a bone wall seal when they had been exploring the undead ruins in their younger days. But right now, these were seals much more ancient in a way.
These seals had been made by someone that wished the vampire race to be gone for good. That wanted the monstrous vampires to be out of the way and in now way their issues any longer.
Therefore, the seals had been made out of stones that naturally held a purifying light affinity. One that caused many of the vampiric monsters to become dormant or even perish when they went near it. The sheer amount of bones around the massive pillars showed the royal dragons that these sealed pillars were definitely valuable in a way.
