If you can use Ebberon it becomes very easy. If you can't Price goes up for rings of sustenance.
1. Get the leadership feat.
2. Get loads of followers that are warforged clerics. It doesn't matter about their class or stats, one level of cleric is a must.
3. Make sure they have the Blackwalker domain from stormwrack.
4. Send them to mine a giant hole in the ocean floor. When they are 1000 feet down, thats 1d6 damage per round (plus the damage they took to get there) to anyone else. The deeps point in earth's ocean is 36,200 feet down or 326d6 damage per minute (average 114 damage per round).
5. Give one of the low level minions your Phylactery(an amulet), and give all others down there a duplicate.
6. Slap on anticipate teleport, Divert teleport, as many anti-divination spells as you can, and repulsion (for the amulets. add
Banality if you can use it)
7. Make some giant castle on the negative energy plane where you are
clearly keeping your Phylactery
8. Have a book at the end of the castle that is titles "the true location of the Phylactery". It is really the book of explosive runes.
9. Realize you can have multiple Phylacteries. (aka. go Voldemort on them)
10. Give some to many minions at the bottom.
11.
12. Profit