If I were a lich…
I would have a super-cryptic and yet painfully precise map that leads to where my phylactery is hidden – a “final challenge” to those who have defeated me. But you’d need to figure out all the clues and codes to get the map to lead you there. But really, the clues are purposefully obtuse and can be interpreted in multiple ways, and yet are exceedingly and needlessly precise (47 feet north-north-west of the shattered stone, without giving any way to find the shattered stone, for instance).
Of course the map itself is my phylactery. I mean that’s obvious if you know me… But who is going to destroy the only clue to finding an enemy lich’s phylactery?
To keep the phylactery from being accidentally destroyed, it isn’t going to be on PAPER of all things. It would be something like a bronze plate with hinges on all four sides so you can flip various “overlays” onto the map to “figure out” the clues. And on the back of the map there is of course a poem that only causes additional confusion as to how the whole thing works and where it leads.
Dyson's Dodecahedron 
If I were a lich man,
Daidle deedle daidle
Daidle daidle deedle daidle dumb…
Brilliant!
Love it Dyson!—both as a general concept, as well as the idea of flipping over the inter-connected “overlays” in layers on the same map page/structure/object!
In The Twisting Stair #2 my article on treasure maps included a table with options for the Treasure Type Medium, and your lich’s map idea would fit right in:
II.D.1 TRADITIONAL TREASURE MAP MEDIUM
Dice Result
1-3 Paper map: papyrus, amate, paper, parchment, vellum, etc.
4-10 Cloth map: piece of cloth, silk, canvas, painting, clothing, rug, tapestry, etc.
11-16 Skin or hide map: human or humanoid skin (human,elvish, orcish, etc.), dragonskin or scales, demon hide, bulette plates, etc.
17-18 Metallic or stone map: engraved, carved, imprinted, or otherwise on a sheet, block, or slab of copper, gold, platinum, mithral, adamantite, etc. (or stone, or a precious stone, etc.)
19-20 Special map
=)
Allan.
Also the box that the phylactery/map leads to opens up to reveal… dun dun dun A MIRROR!!
Oh no, I would work out a number of places you might think the map leads to and put things in each that seem to work with the map in some way.
More overlays you can attach, ‘hints’ about the ‘cypher’ used for some of the labels on the map, things you can place the map on to ‘provide context’, etc. All things to make sure everyone knows that you need the map to find the phylactery.
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