Shadow Caster Question

[Yogibear41]

Do Shadowcaster fundamentals become usable at will at 14th level if you use a prestige class to advance your mystery casting or do you actually need to be a 14th level shadowcaster?

For example could a shadowcaster5/Master of Shadow10 (effective shadowcaster 14) use fundamentals at will?

[gorfnab]

The sample Master of Shadows character on page 124 and 125 of ToM is Shadowcaster 6/ Master of Shadows 10. It's Fundamentals are listed as at will.