Voadam said:...Becoming a lich should not be an easy thing to do. Just making an item capable of being used as a phylactery for that character should not be sufficient, only the first or an intermediary step.
Don't make liches less powerful, just make them really tough to accomplish.
So should this player be penalized 5 levels for playing by the rules? Should the lich also be penalized 5 levels for playing by the rules (and paying on top of that)? These are *major* Rule 0 items to say "this is wrong; you must play a 5 level PrC to get this". I admit that as a DM I'm verrrrrry unlikely to allow a player to get a template [ANY template], but if they do, personally, I'm not going to then charge them tens of thousands of experience points for having succeeded on such a task.
Voadam said:While I think that can be a fine route to becoming a lich, there are some problems if that is the only way. It won't match up to the template in the MM. You will have five levels of hit points, BAB advancement, save advancement and skills. Plus it will add +5 to CR instead of +2.
That is a +4 to will save and +1 to ref and fort at level 5
You wouldn't have a level 12 wizard with the lich template, you'd have a 12wizard 5 lich.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.