Mythic Permanency artifact

[Limas Venomscale]

I'd like to create a mythic greater artifact that can cast the Permanency spell (limited times per day, up to 3 max with a maximum of 9 total spell levels per day) but can burn Mythic power instead of diamond dust, how many mythic points per 1,000gp would you recommend ?

At most I'd want it that at tier 10 (23 mythic points, draining everything) would allow for permanency for spells with a cost of 22,500gp but spells such as Lost Locale (cost 90,000gp) or Yellow Sign (40,000gp) are beyond it's capability except under special circumstances or coming up with the full cost in diamond dust.

Also the desired spell to be made permanent, must be supplied separately.

[Mysterious Stranger]

So what you want is a way to cast unlimited number of Permanency spells? Mythic points are a renewable resource that refresh every day. Being able to cast Permanency with mythic points instead of gold is no different than being able to cast them from free. You already answered your question with your second paragraph. 22500/23 = 978.26 which would be about 1 mythic point per 1,000 gold.

I am assuming you are the GM in this case because this is definitely in the realm of GM’s option. Even for a mythic campaign this item is overpowered and will unbalance a campaign. As a GM this is something I would never allow in a campaign.

What you may want to consider is instead of allowing it to cast permanency to allow it to extend the duration of a spell to 24 hours like the hierophant path ability enduring blessing. While the spell would not be permanent it would allow it to be used on more spells. Let it work on up to 3 spells with a duration of 1 round per level a day. This gives the player more flexibility as to what can be extended, but at the same time avoids allowing the player access to an unlimited number of permanent spells.

[Themetricsystem]

I would simply put, never hand this over to a a player, that is unless I am for some reason doing a 1-1 game with a friend and we want to tell some specific story which requires this kind of thing.

I would NEVER NEVER NEVER NEVER allow a PC to spend some resource that regenerates daily in place of Wealth/Material Components, for reasons why, see the discussion on these boards involving Blood Money.

If you want to move forward with this, I would advise INSTEAD of using Mythic Points, I would change it to an incurable STR/DEX/CON (All three) Penalty of -2 for every casting of Permanancey, make it so the character can choose to dismiss the effect and restore the "life force" to themselves.

[Jonas Seaborn]

The mythic feat eschew materials allows using 2 mythic points for 100gp per tier, you wouldn't have a level 9 spell limit but it would be closer to the rules.

[OmniMage]

I might allow this for an epic game. I would rule to have an unlimited ability to cast permanency, you also need to cover material components cost for a 100 times. For instance, the ability to create a permanent Comprehend Languages or Detect Magic (normal cost 2500 gp), would cost cost you an additional 250,000 gp in material components.

Emphasis on the epic part. I think if you're epic characters, you should be, well, epic. Some of the rules should be adjusted to make you better than normal characters.

I also want to point out that 250,000 gp is more expensive than a weapon with 10 levels of bonuses (200,000 gp). This is beyond the wealth range of nearly everyone but the highest level characters (or epic characters), even mythic characters.