What is mythic?
The mythic rules offer a new way to play Pathfinder. It uses all the rules that you are familiar with, but it adds a new layer to the game. Mythic adventurers are elevated above their non-mythic counterparts, gaining powers and abilities beyond their reach that allow them to take on tougher foes and more daunting challenges. A mythic character takes on the agents of deities, rushes headlong into the abyss, and strives to build a legend, all while facing off against a wide variety of foes, from common monsters to other mythic characters. If Elric, Fafhrd, Gray Mouser, Hercules, or King Arthur were created in Pathfinder, they would be mythic characters.
Is mythic a replacement for epic rules?
No. "Epic" rules generally mean "rules for characters above level 20." Unlike epic rules, you can use the mythic rules with 1st-level characters just as easily as you can with 20th-level characters. You can even use the mythic rules to continue to grow in power once your PCs reach 20th level, taking on some of the toughest adversaries in the game, from ancient dragons to demon lords. Meanwhile, a low-level mythic character might take on monsters that you are already familiar with, at a level where non-mythic characters would face certain doom.
How do the mythic rules work?
Your mythic character selects a mythic path, which grants a few general abilities. For example, you gain the ability to draw on your mythic power a few times per day, altering a d20 roll after you've rolled it. Mythic characters are also more durable, gaining additional hit points.
You begin as a 1st-tier mythic character. You don't gain mythic tiers by accumulating experience points. Instead, you have to accomplish a campaign-specific goals (as decided by the GM) to advance to the next tier. Using this system, your mythic tier is not tied to your character level. You still gain XP as normal, and still gain levels as normal, but occasionally you might increase your mythic tier as well, adding a few new mythic abilities and powers to your character.
There are 10 mythic tiers. By the time you've reached the 10th tier, your character is nearly unstoppable, almost the power of a demigod (in fact, one mythic ability you can choose is the power to grant spells to your followers).
It is important to note that while mythic rules add to the game, they do not necessarily make the game more complex. A new mythic abilty might allow you to automatically succeed a roll, or ignore an attack of opportunity, or bypass some other rule that slows down gameplay. Mythic isn't about adding more math to your character, it's about allowing your character to do amazing, heroic things that aren't normally possible with the normal rules.
Are there mythic monsters?
Yes. Mythic Adventures includes 40 familiar monsters (barghests, demons, dragons, giants, owlbears, and so on) upgraded with mythic abilities so they can challenge mythic PCs. The book also includes several new mythic templates for quickly adding mythic abilities to a monster, rules for customizing new mythic monster, and new universal monster rules for mythic creatures.
Bestiary 4 (available late 2013) includes additional mythic monsters.
DR/Epic: How do the new rules for overcoming DR/epic (page 7) interact with weapon special abilities that have variable enhancement bonuses, such as bane and furious?
Essentially, there are now two ways to overcome DR/epic with magic weapons.
The first way is presented in the Universal Monster Rules in the Bestiary: You can use a weapon that has an actual enhancement bonus of +6 or higher. Currently the Pathfinder RPG has no weapons with a permanent +6 or higher enhancement bonus (though you can temporarily achieve a +6 or higher enhancement bonus with certain magical or class abilities).
The second way is presented in Mythic Adventures: You can use a weapon that has a total "plus-equivalent" of +6 or higher. For example, a +1 vorpal longsword and a +2 flaming frost shock keen longsword both are +6-equivalent magic weapons.
A weapon with a conditional or variable enhancement bonus, such as bane or furious, gets the best of both options. As a baseline, it include the plus-equivalences for its enhancement bonuses and special abilities; when the conditional or variable enhancement bonuses activate, it adds those to its total as well.
For example, a +3 undead-bane longsword is a +4-equivalent weapon, which on its own is not enough to overcome DR/epic. When used against an undead creature, its enhancement bonus increases by an additional +2, making it effectively a +6-equivalent weapon (+3 baseline enhancement bonus, +1-equivalent from bane, +2 conditional enhancement bonus against undead from bane) and therefore able to overcome that undead creature's DR/epic. (Another way of looking at it is when bane is active, you add its conditional +2 enhancement bonus to the weapon's normal +4-equivalent bonus, temporarily giving you a +6-equivalent weapon).
Mythic Form of the Dragon: Mythic form of the dragon says that it increases my breath weapon damage to 10d6, but 10d6 isn’t actually an increase for form of the dragon II or III. Does that mean the mythic version reduces my damage?
No, instead mythic form of the dragon should increase your breath weapon damage by 2d8. This will be reflected in the next errata.
Mythic Vampire, Overcome Weakness: How is this ability better than a standard vampire's weaknesses?
The mythic vampire should only be sickened in direct sunlight, not nauseated.
Also, unlike a standard vampire, a mythic vampire should not be utterly destroyed on the second round of exposure to direct sunlight (it will take 10 points of damage each round, lose its fast healing, and be sickened, but can otherwise take actions and survive as long as it still has hit points).
This will be corrected in the next printing of Mythic Adventures.
Why do the "inspired spell" and "wild arcana" path abilities have slightly different rules text?
These two abilities should function the same and (other than they affect divine or arcane spells) have identical rules text. They also need some clarification about what spells you can cast with either of these path abilities.
The proposed text for these two abilities (pending an official errata of the Mythic Adventures book) is:
Inspired Spell (Su): As a standard action, you can expend one use of mythic power to cast any one divine spell without expending a prepared spell or spell slot. The spell must be on one of your divine class spell lists (or your domain or mystery spell list), must be of a level that you can cast with that divine spellcasting class, and must have a casting time of "1 standard action" (or less). You don’t need to have the spell prepared, nor does it need to be on your list of spells known. When casting a spell in this way, you treat your caster level as 2 levels higher for the purpose of any effect dependent on level. You can apply any metamagic feats you know to this spell, but its total adjusted level can’t be greater than that of the highest-level divine spell you can cast from that spellcasting class.
Wild Arcana (Su): As a standard action, you can expend one use of mythic power to cast any one arcane spell without expending a prepared spell or spell slot. The spell must be on one of your arcane class spell lists, must be of a level that you can cast with that arcane spellcasting class, and must have a casting time of "1 standard action" (or less). You don’t need to have the spell prepared, nor does it need to be on your list of spells known. When casting a spell in this way, you treat your caster level as 2 levels higher for the purpose of any effect dependent on level. You can apply any metamagic feats you know to this spell, but its total adjusted level can’t be greater than that of the highest-level arcane spell you can cast from that spellcasting class.