Shadowcaster Feat Question

[Senyu]

I have a question about utilizing a few feats in the Shadowcaster class that I'm not certain would work. To begin, the Shadowcaster has this passage beneath the Mysteries and Paths section.

When you reach 13th level and become capable of casting master mysteries, another change occurs. Your master mysteries now function as arcane spells, and your initiate mysteries function as spell-like abilities.

Page 112 Tome of Magic

If Master mysteries now function as arcane spells, would that mean I could apply metamagic feats such as Extend Spell? If I can, there's another step that I'm curious about. There is a feat in the Tome of Magic that can make mysteries cast as a spell-like ability if they are a spell.

FAVORED MYSTERY
The mystery you choose becomes easier to cast.
Prerequisite: Ability to cast mysteries.

Benefit: Choose a mystery you know. You cast that mystery as a supernatural ability instead of a spell-like ability, or as a spell-like ability instead of as a spell. If you choose a mystery that you cast as a supernatural ability, or if you later gain the ability to cast that mystery as a supernatural ability, you gain an extra use of that mystery per day. This feat does not otherwise increase the number of times per day that you can cast the chosen mystery.

Special: You can take this feat multiple times. When you take the feat again, you can choose to affect the same mystery or a different one.

Page 136 of Tome of Magic

If this works and I'm now able to cast a mystery that was a spell as a spell-like ability, would the spell metamagic feats like Extend Spell still apply?

My end goal is to essential apply both shadowmagic metamagic feats and spell metamagic feats to a mystery that is a spell with the goal of doubling effects with similar metamagic effects. And if the spell is considered level 9, and then is raised two levels by the spell metamagic feats, would casting it as a spell-like ability make it legal to cast? I'm sure there are many broken and not possible things in this goal, but I was just curious on the technical details regarding this goal.

The 9th level spell in question is Black Labyrinth which can be found in the Cityscape book Part 2 urban magic and I'm trying to apply two instances of extend range and duration by using the feats Enlarge Mystery [METASHADOW], Extend Mystery [METASHADOW], and Favored Mystery which can be found on page 136 in Tome of Magic, and Extend Spell [METAMAGIC], Enlarge Spell [METAMAGIC] from the Player's Handbook page 94.

 

[Shin Okada]

If Master mysteries now function as arcane spells, would that mean I could apply metamagic feats such as Extend Spell?

I say no because mystery users don't have spells slots. Mystery per day is different from spell slots. And thus you cannot spend appropriate spell slots needed for metamagiced spells.

If this works and I'm now able to cast a mystery that was a spell as a spell-like ability, would the spell metamagic feats like Extend Spell still apply?

Basically, metamagic feats only work for spells and not for spell-like abilities. The only exception I can think of is sudden metamagic feats. The rule regarding sudden metamagic feats and spell-like abilities are written in P.71 of Complete arcane.

You may use dedicated metamagic-like feats for spell-like abilities (such as empower spell-like ability feat in MM), if your caster level is high enough. I don't know if there are feats such as extend spell-like ability or enlarge spell-like ability, though.