Phylactery or graveknight's armor with Sequester could be slightly challenging to locate. You'd have to touch the thing first to be able to locate it with Discern Location - which is the most powerful divination spell available.
Sequester would also turn said object invisible. I can only imagine how hilarious a graveknight would look with an invisible armor.
To make things even more interesting I used Contingency as a trigger for Teleport (Plane Shift and Greater Teleport were fun too, but bit too expensive) so that whenever the graveknight is destroyed the armor teleports to a random location within 900 miles.
After this happens a few times I suppose a group of adventurers will use something to block the teleport.
Now, I admit that it would almost have been easier to make the armor intelligent. It's a bit more interesting (and less challenging) this way.
So here are the bits that interest me rule-wise: does Sequester actually work like this when used as a special property on a magic item? Is it even possible to use Contingency as a trigger for magic items? Can graveknight's armor (or lich's phylactery) be an intelligent item? If so, locating them would be insanely difficult.
