Okay, so I'm still poking about in the Adventurer Conqueror King System (ACKS) Player's Companion following my triumphant(?) use of the riches contained therein to recreate the White Monk class from Final Fantasy.
The core concept in creating custom classes for ACKS is allocating your build points (BP). You get four BP and you have five class categories into which you may allocate them: Hit Dice, Fighting, Thievery, Divine, and Arcane. Obviously the four categories align with the basic four class types in D&D so essentially you're mixing and matching the four for your base. Each category actually starts with a value of 0 and you can leave a category at 0 if you wish while allocating BP elsewhere. Custom racial classes get 8 BP to start, but their maximum level will be affected depending on how many points you actually use.
But then I thought, what if you put all four of your BP into Hit Dice Value? That would be kind of a wierd class. Well, you'd look like this:
Hit Dice Value: d12 [XP Cost 2000]
Fighting Value: 0 (like a mage)
Attack Throws: +2 per 6 levels
Weapon Selection: Restricted (choose four of: club, dagger, bola, dart, sling, sap, staff, whip)
Armor Selection: Forbidden
Fighting Styles: 1
Damage Bonus: none
Thievery Value: none
Divine Value: none
Arcane Value: none
Saving Throw Progression: should be based on highest value of Arcane, Divine, Thievery, or Fighting, or if tied then whichever comes first as just listed. But our Hit Die Hero class (?) has 0 in all of those, so the default, based on the priority, is Arcane progression.
Prime Requisite: according to the rules this should be based on your saving throw progression, which would be mage here, making INT the Prime Requisite; we'll you'll be good at riddles anyway.
Strongholds and Followers: hmm, again this is based on your Fighting/Divine/Mage/Thievery value; but this class doesn't have any values in any of these. As per the rules this class doesn't actually meet the minimum requirements for a stronghold. I guess you'll have to go back to your little village and fend off sponging relatives when you retire.
XP per Level: starts with needing 2,000 XP for level 2 and progresses as per p.85 of the ACKSPC.
But what the heck sort of class is this? You're naturally resiliant, but can't wear armor, can't fight, can't cast spells, have pathetic weapons, and will never rule a stronghold...hmm, kind of sounds like Bilbo.