I did finish the corruptions to the classes the group is going to be playing in at least, and I figured I would share them here.
At the moment they have:
Barbarian - my wife
Cleric - my cousin
Witch (slightly modified from pathfinder) - my other cousin
Psion, or Ranger - my friend can't make up his mind on which yet
Rogue - NPC
We start playing Friday night (10/18/13) and hopefully it goes well, I'm going to be relying and hoping on their ability to explore more instead of me pointing them in a specific direction (first time most have done this so not sure how well it will work out yet).
But here are the corruptions I've worked up, and yes mostly they make them stronger which I am factoring into how the game is going to go.
v Potions found in the Mournland function normally for you, all others function half as well.
v While in the Mournland, at the end of every round there is a 25% (this chance drops to 10% while outside the Mournland) chance that the spells cast during that round could possibly turn into living spells, if a cleric and wizard both cast a spell there is a chance the spells will merge to form a stronger living spell (ECS. 294) which lasts for 1hr per half its HD while in the Mournlands (this drops to 1rd per HD outside of the Mournland). You can attempt to gain control of the Living spell by making a Caster Level Check, whatever you roll is what the Living spell must beat with a Will save. If it fails this save then the caster can control it until it dissipates.
v You take a -10 penalty to CHA based checks when dealing with people/creatures not corrupted by the Mournland.
v Healing spells function normally while in the mournlands, and only heal half as much outside the mournlands.
v Whatever Holy Symbol the cleric possesses has been transformed into an identical holy symbol except it’s now purple and made of Mournlode (deals your level in damage to undead you turn).
v While in the mournlands clerics gain an additional Domain in addition to their normal 2 (for a total of 3 domains), you can also cast one additional spell per day but it has to be from this extra domain.Extra domain choices: Darkness, Decay, Destruction, Madness, Pestilence, or Shadow.
v When turning undead a cleric can choose to twist the energy to instead turn a non-warforged creature that is not corrupted by the Mournland. (This functions exactly like turn undead).
v **Turning undead might be changed to channeling energy similar to pathfinder if I can sit down and write the rules out for her.**
v Your patron has not been affected but the effects of the Mournland have affected your mind which manifests in the form of a second patron although it must be from this list: Death, Insanity, Plague, or Shadow. This second patron is only active and follows you around while you are in the mournlands.
v You also gain one new spell of each spell level but this extra spell must be pulled from the list of spells you secondary patron grants you.
v Your familiar gets warped and grows to a medium size, and it also gains the Mage-bred template.
v Your rage works in reverse, you are constantly in a rage state and you can use your daily rage uses to instead clear your mind for a short time.
v While in the Mournlands your DR is increased by 1 (this stacks with your other DR from the barbarian).
v While in a rage state your STR & CON is increased by another +2, and your AC is dropped by an additional +2. Also while raging you move an additional 10ft. faster.
v The Rangers companion is corrupted by the Mournlands and gains the Dark Creature template (Tome of Magic pg. 161) although you can choose which element it is resistance too at creation.
v Rangers gain one extra spell slot for each level and they can choose any spell they could normally cast for that spell.
v Rangers also gain one extra favored enemy that has to be one of the following: Aberration, Construct, Monstrous Humanoid, Outsider (air, good, lawful), or Undead.
v Your psicrystals personality splits letting you choose a second personality to reside in your psicrystal. You gain the bonuses from both.
v You have gained a deeper understanding of one element. You choose one element from Acid, Fire, Cold, or Force. Anytime you manifest a power with this element you can add in two extra power points (from your own pool) over what the maximum you normally could. This means you could manifest a power with more modifications than you normally could.
v Anytime you manifest an astral construct it gains one additional choice from whatever menu it has access to. Only one extra choice is given total.
v If you choose to have an Elemental Envoy through the feat instead of a psicrystal then your elemental envoy is corrupted and has the Phrenic creature template applied to it (EPH pg 206).
v You gain an uncanny ability to blend into your surroundings granting you to gain a +5 bonus to hide and move silently.
v You have an easier time focusing in one opponent’s weak spots; this grants you an additional +1d6 to sneak attack damage.
v Although you don’t quite understand it yet, you have the ability to sneak attack undead creatures now. You can’t critical hit them for some reason, but you can apply your sneak attack when appropriate.