I kind of like the idea of some inbred royal servants... rats whose fur is also practically white. They'd be like Cleverness +1, but have less Brawn than a regular rat. Their Magic rating might not be as bad, either.
Rather than have a ton of spirt-based Summoning effects, it might be better to have two classes of magic available... Wizardry (affects the real world) and Sorcery (affects the spirit world). There could be six standard spells for each and a separate Edge for access to each one.
Wizardry:
These should mostly be Edges that require two Advanced Edges already. Let me browse a few ideas...
Call Storms (requires Levitation and Lightning): the caster must float up into the sky or occupy a high point.
Okay, ways to perform forbidden magics... These would probably mostly be Edges.
Shapeshifting (Requires the Edges: Binding and Shaping): by conjuring a powerful spirit into your own flesh and granting it the ability to remake your own form, you can be physically transformed in ways that regular flesh-Shaping can't match, such as growing larger or smaller or acquiring special abilities like a venomous bite.
The difficulty is based on the form desired. The process is quite violent but very quick, taking only a few rounds. You won't be able to act during the process, but physical harm suffered at this point is commonly washed away... only a blow which kills you outright will have any effect; lesser wounds simply close up during the process.
The process requires both a Binding and Shaping check vs the same difficulty. If the Binding check fails, you'll end up with the spirit in charge of your new form instead of yourself, effectively making your character into an NPC for the duration. The only way to undo this is to successfully Banish the spirit. You can spend a Hero Point to make one attempt to Banish the spirit yourself before it's too late; otherwise you become a prisoner in your own horribly remade flesh until the spell ends... Since the spirit then has control over all of your physical and magical actions, it can maintain the spell itself as long as it wants.
If the Shaping check fails, the form will be imperfect. This generally means that your new form is hideously disfigured and generally has vulnerable spots where the bones, scales and/or protective shell haven't formed properly.
If either check botches (fails by 10+), you don't change and instead take 1d6 damage per failure level. If you botch both checks, you'll probably die.
Shapeshifting of this sort is hard on the system. Your real body takes 1 point of damage every so often; when this exceeds your regular Hit Point total, you have to make a Survival Test as per normal.
Maintaining your new form requires minimal concentration. If you are knocked out, the spell will end and you will revert to normal. It can be maintained while you sleep by spending an hour meditating beforehand, however. The transformation can be made permanent by Severing the spell, but doing so incurs as many Severance points as the base difficulty divided by 5 and the decision of whether or not to Sever has to be made before you roll either check.
Some possible difficulties:
So, let's say that one of the First Ones desired to become a Titan. That would entail rolling Summoning and Delve, both vs difficulty 50. If he had a skill of +15 in both and a Magic stat of +15 to back it up, he'd "only" need to roll a 20+ on both to pull it off. If he succeeded, he'd take 1 point of stress damage per round and when that exceeded his natural Hit Points he'd have to start making Survival tests. If this knocks him out, he returns to his natural state, multiplies any damage taken to his Titan form by an appropriate amount (i.e.- if he's lost 5% of his HP as a Titan, he'll take 5% of his regular HP total in damage when he changes back) and adds that to his stress damage to see how much damage he's taken in total.
Okay, assuming that a skill of +5 is basically Journeyman, a +10 is Master and a +15 is Grandmaster...
Typical Common Mouse (stats at +0 not shown): Magic -2
Agility: -10 inanimate object, -5 slug, +0 typical person, +5 acrobat, +10 astounding acrobat.
Brawn: -10 inanimate object, -5 immobile person, +0 typical person, +5 big, strong man, +10 Olympic weight lifter.
Cleverness: -10 insect, -5 animal, +0 typical person, +5 genius, +10 supergenius.
Drive: -10 inanimate object, -5 coma victim, +0 typical, +5 strong leader, +10 amazing leader
Perception: -10 inanimate object, -5 insensible, +0 typical, +5 eagle-eye, +10 bloodhound.
Magic: -10 inanimate object, -5 ordinary animal, +0 talking animal, +5 mage, +10 archmage.
Size: -10 flea, -5 ant, +0 mouse, +1 rat, +5 weasel, +10 ka'at, +20 human.
Size makes you easier to hit with ranged attacks, but subtracts from all damage taken and adds directly to Brawn.
Ant: Agility +1, Brawn -5, Cleverness -10, Drive +0, Perception +0, Magic -5. HP: 1, Armor 1.
Soldier Ant: Agility +0, Brawn -3, Cleverness -9, Drive +1, Perception +0, Magic -5. HP 4, Armor 2.
Common Shrew: Agility +2, Brawn -1, Cleverness -7, Drive +0, Perception +1, Magic -5. HP: 8.
Talking Shrew: Agility +2, Brawn -1, Cleverness -3, Drive +0, Perception +1, Magic -3. HP: 8.
Weasel: Agility +1, Brawn +5 (from size), Cleverness -6, Drive +2, Perception +1, Magic -5. HP: 20, Armor 5.
Ka'at: Agility +3, Brawn +10 (from size), Cleverness -5, Drive +0, Perception +2, Magic -5. HP: 30, Armor 10.
Human: Agility -1, Brawn +20 (from size), Cleverness +0, Drive +0, Perception +1, Magic -5. HP 50, Armor 20.
Spirits won't/can't inhabit a living body for long, because they don't like fighting with the host for control. The only way to get them to stay reliably is to drug the subject so that they are basically insensate and the spirit gets to be in charge.
Sling: damage 1d6+Brawn/2. Reloading takes a Secondary Action. Very cheap.
Shortbow: damage 1d8+Brawn. Reloading takes a Secondary Action.
Longbow: damage 1d10+Brawn. -1 to hit. Reloading takes a Secondary Action. Requires a minimum Brawn of +1.
Crossbow: damage 1d10+1+Brawn. +1 to hit. Reloading takes a Full Action. Expensive.
Optional Rule: all missile weapons except for Slings are built for a particular Brawn rating. If your Brawn is less than that, you are at -2 to hit and damage per point you fall short. If your Brawn exceeds it, your damage bonus is calculated as though you had the Brawn rating of the weapon.
Toughness (Fortitude): roll Brawn + Drive + Size
No Reflex save... that's under the Reaction skill.
No Willpower save... that's under the Resolve skill.
Only physical fortitude (used for resisting stuff like poisons, diseases and electrical shocks) is based solely on stats. Diseases should probably leave out Size, though.
Delve Effects
Note: using Delve always requires 2 Full Actions to cast and requires a Full Action each turn to maintain. It can only be performed by touch.
Influence Effects
Manipulate Effects
Mislead Effects
Scry Effects
Spark Effects
Summoning Effects
Spiritlore Skill: lets you determine what sort of spirits are likely to be found in an area and the best conditions for summoning them. Necessary to keep the Binding power from being more than a crapshoot.
Variants: some spirits possess strange powers above and beyond what's typical.
Destroyers: some can remake a dead body into a monstrous form.
Healers: a few aren't good at healing, but can restore the recently dead. They will only enter a recently deceased corpse, and then only one that's in good shape. Once successfully summoned to revive someone, they never return to the same spot again.
Time required per session:
There's a Perform specialty called Waterdancing. It's combined with Shaping to make liquids dance and reshape themselves in entertaining ways. It's a performance art popular amongst the upper classes.
When you cast a Shaping spell on something, you can roll over your successes to the Craft/Medicine/Herbalism/Perform roll.
Hm. How about this: every extra success you get beyond the minimum shifts the time required down a step... nah, that would require a big chart or else it would be too powerful. There probably should be a minimum difficulty for each one, though.
Knife (light): can be used in close combat without penalty (normal penalty is -4 for a light weapon and -8 for a medium or heavy weapon).
Mace/club (medium or heavy): can inflict stunning blows (3/4 of damage is stun) at its normal damage roll (normally a subdual attack with a lethal weapon does 1/2 damage). A club is just an inferior mace.
Axe (medium or heavy): when used to perform a Full Attack (a full action), you are +4 to damage (normal is +2 to damage).
Spear (medium): when used to fend, you don't have any penalty to hit if the foe doesn't advance (normally you're -2 to hit if they don't advance, +2 to hit if they do).
Sword (light, medium or heavy): if you score a critical success on a parry, you can apply roll-over dice from it to your next attack upon that person.
Flail (heavy): if your attack is successfully parried by less than 5 points, you still score a partial success and strike them for half damage. If you try to use a flail to parry, the same applies to you.
Staff (medium): reduced damage, but gets an extra free parry per turn.
Beat/Feint (secondary action): make an attack that tries to throw your opponent off-balance. If you win, it does no damage, but you get to roll-over your Success Levels as Bonus Dice to your next attack (which must be in the same or next round).
Minor Attack (secondary action): make an attack which inflicts 1/2 normal damage if it hits. Eh, probably a bad idea.