Antara said:
Can you say something more about mythal mechanics? How hard is it to make one? How powerful can it be?
They can be almost as powerful as you want. Granted you can pull it off, of course.
It uses the Epic Magic mechanic, with the new Seed: Mythal. You can have Prevalent spells (these are always active), Arointed spells or spell groups (those won't work within the mythal), Vanguard spell (those can be cast by anyone within the mythal with just a command word, either at will, 3/day 1/day ) and other prevalent powers (stuff that cannot be defined by a spell). You can also limit the area of certain components, can make the powers spell trigger only (so only spellcasters can use it), and key them (so only certain types of creatures or individuals can use the powers). Every power has a component cost. You add up all component costs, divide by thousand, and add the value to the Spellcraft DC. You can use the usual factors and mitigating factors, plus a couple of special factors (like caster dies, resurrection impossible, that gives a hefty cost adjustment downwards). Then you cast the spell and you're done.
These spells aren't made for repeated casting, and are no combat spells, either, so you can have a long casting time, use ritual casting with lots of support casters, and you can also take backlash and likely XP cost (for casting it once, this will probably lessen the XP you have to pay, since development costs XP, too)