I've asked my partner to help me playtest some of the Mythic stuff, and he created TWO characters to run through the beginning of Shattered Star.
The characters:
Ragor, male Dwarf
Barbarian 1 / Champion 1
Champion Strike: Fleet Charge
Path Ability: To the Death
Feat and Mythic Feat: Toughness, Toughness (Mythic)
Flaw: Acid Vulnerability
*Uses a 2h reach weapon
Dalgrin, male Dwarf
Druid 1 / Hierophant 1
Divine Surge: Recalled Blessing
Path Ability: Water of Life
Feat and Mythic Feat: SF(Conj), Mythic Spells (CLW)
Flaw: Hubris
*Has a Roc companion, but wants to choose the domain instead. Plans to go summoning route
I rolled the Flaws (1d8) to avoid "both my characters are dependent on ale.. they're dwarves after all".
The test: see how these 2 characters hold up against an AP designed for 4 players.
Sadly, the initial encounter was an absolute joke because I couldn't roll for crap.. Not to mention the enemies only do 1 damage (1d2-4) in melee. The 1st level Tier 1 characters have 15 (druid) and 26! (barb) HP.
Things that will prove difficult: the Toughness/To the Death combo is fantastic... almost too fantastic. Neither ability costs any mythic power. Especially since Mythic Toughness can be taken at tier 1, I can see many defensive builds going for this combo very quickly. Drop to -1, gain DR10/epic. Why heal when the barbarian can go to -48 Con (or -60 when raging)? If he gets in the -20 or less range (if any monsters at this level can bypass his DR10) then the Empowered Mythic CLW for 3d8+2 will heal him just fine!
*Where the barbarian is right now, he has 74HP to burn through before he dies... At level 1. While maybe not so bad on a L5/T1 character this is incredibly strong and I think that the barbarian could solo most of what will be thrown at him. Plus DR10/epic (which nothing will have unless I add in mythic to the AP).
Mighty Summons! I'm both glad and shocked he didn't pick this ability for his summoner. One use of Mythic power to give his summons the ability to act twice in a turn... Scares the daylights out of me. He said he would likely take it on his next tier when his summons last longer than a round (fair enough).
Things that need clarification: Water of Life. By RAW you can drink your own potions to maximum effect... So a L1/T1 CLW, if made Mythic, will heal for 26 damage to the caster. That's quite a bit. If the Maximize/Empower combo isn't supposed to work together then this needs to be specifically said.
Feat: Mythic Spells. It gives you quite a bit of bang for your buck, in the sense that it will give you (over the course of a mythic campaign) up to 10 Mythic Spells. The Special section wording is a little confusing.
What I would like to see:
-More Path abilities that deal with opportunities outside of combat.
-More Mythic feats without prerequisites (he didn't get the feat list until both his characters were already done, and was blown away enough by toughness to take it)
Once we delve into some more combat (there was only 2, the second being against a single sorc3 which any 2 1st level characters could likely take down) I will try and provide some more feedback on encounter balance.