Mythic Legendary Item Undetectable reads: "This grants its bonded user the ability to become utterly undetectable while invisible. While invisible and in physical contact with this item, the bonded creature can’t be detected or scryed by any method."
Lvl 20 Hidden Master reads: "At 20th level, a ninja becomes a true master of her art. She can, as a standard action, cast greater invisibility on herself. While invisible in this way, she cannot be detected by any means, and not even invisibility purge, see invisibility, and true seeing can reveal her. She uses her ninja level as her caster level for this ability. Using this ability consumes 3 ki points from her ki pool. In addition, whenever the ninja deals sneak attack damage, she can sacrifice additional damage dice to apply a penalty to one ability score of the target equal to the number of dice sacrificed for 1 minute. This penalty does not stack with itself and cannot reduce an ability score below 1."
That's a bit of a text difference. Now, the way I've been running Legendary Undetectable is that you can't be detected, or scryed on - "because mythic" - by any means. However, things that cancel INVISIBILITY still make you visible; namely evocation (not scrying or divination) spells that cancel invisibility. They don't detect you, so much as they simply cancel the invisibility. That seemed to make sense until I'm pitting the party against a level 20 ninja who as Hidden Master. Which turns out to be "better than Undetectable".
So the verbiage is "utterly undetectable while invisible" versus "cannot be detected by any means, and not even invisibility purge, etc... can reveal them". Nothing in the first verbiage indicates that they can't be revealed with purges.
So I mean, besides screwing over the players with multiple save or die chances, do you think the reconciliation of these two abilities this way makes sense? Presumably a anti-magic field would nuke both abilities (unless they somehow had tech/natural invisibility).
... do you think the reconciliation of these two abilities this way makes sense?
No.One is a capstone for a class that emphasizes stealth, the other is a mythical magic item property.
They aren't related and the mythical ability isn't necessarily as strong as the class capstone ability.
Presumably a anti-magic field would nuke both abilities (unless they somehow had tech/natural invisibility).
By selecting the legendary item universal path ability more than once, a mythic creature can transform a normal legendary item into either a minor artifact (if the character chooses it a second time) or a major artifact (if the character chooses it a third time).
If the mythic item is an artifact it is unaffected by the AM field. If the mythic character becomes invisible using a power of the item, it could work even in an AM field. It depends on the invisibility effect description.