Um... you realize that the Lich has to be able to come out of his phylactery, right? I mean, it's fine to have your Phylactery all safe and whatnot, but the reason that every Lich doesn't just hide his in the middle of a lava flow and wait for it to cool is because once the lava hardens, it's not gonna be any use to him, since there's no way he can come out of it. You kinda can't enclose it within an inch of adamantine and put all sorts of nasty spells on it if you want your Lich to be able to make use of it.