Shadowcraft Anima mage help with higher levels

[vhati]

I am currently playing in a campaign where roleplaying, versatility, changing form and being always ( and all day long) prepared is important. We are currently level 8 and after the next 'downtime' session we will be level 9. We are allowed a retraining of our characters and the DM wants to loosely know what to expect on higher levels. It is currently unknown at what level we will stop but we will at least be level 15.  So I am thinking of a level 20 build just to be sure. I have read the handbooks for binders, shadowcraft mages and anima mages but still need some help.

The other members of my party are a changeling bard5/chameleon3 who has jack of all trades and can add half her bard level to skills (minimum of +5 to all skills), and a shifter druid 8 (lost wildshape for shapeshifting ACF)
after talking to the players  I found out that the end builds will probably be bard 7 / chameleon 10 / recaster 3 and druid 8 / moonspeaker 12.

My build:

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male N Whisper Gnome

for roleplaying purposes I have a tie to the plane of shadow and I am the guy for the knowledge skills and to identify creatures(skill trick: collector of stories)

Illusionist 1-2 / Binder 1 / Illusionist 3/ Anima mage 1-2 / Shadowcraft Mage 1-3 / Anima Mage 3-10 / ??? 3

Str 10
Con 14
Dex 17
Int 17 -> 18 eventually 21
Wis 13
Cha 13 -> 14

Feats:  (2 flaws, 1 trait)
1 Heighten spell, Earth sense, Earth spell (flaws: noncombatant, vulnerable, trait: Spellgifted(Illusion)) trade scribe scroll for Improved Initiative, Gnome Subtitution Level 1, focused specialist.
3 Improved Binding
6 Spell Focus Illusion
9 Residual Magic
12 Echoing spell
15 ...
18 ...

At level 12 I can 1/day free heighten Silent Image to max level and then use residual magic the next turn to cast an echoing Silent Image again freely  heigthened to the same level and get it back 4 hours later at -4 cl. Alternating between free echoes and free heightens I will lose a cantrip and gain the rest of  spells back four hours later.

Vestiges that I will be binding quite often and the abilities from them I am interested in:
Naberius: all
Focalor: Aura of Sadness
Buer: Buer’s Knowledge, fast healing, healing gift
Tenebrous: rebuke undead
Dantalion: DAntalion knows
Chupoclops: Aura of Despair, Ethereal Watcher, Soulsense

Some important information about the campaign

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I do not use alter self /polymorph chain
skills are actually important
no arcane disciple(luck) for a lot of miracles
no dragon / 3rd part material
eberron / forgotten realms  specific material allowed
DM can refuse things on a case by case basis

So where do i need help?

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What are good options for the last 3 levels
2 more good feats ( spell rehearsal, extend spell, persistent spell, signature spell, arcane thesis, others?)

are the alternate class feature unearthed arcana worth it?
- Chains of disbelief trades a familiar, good?
- shadow shaper trades bonus feats of 5th / 10th / 15th level which I probably will not get anyway, for hide as a class skill and will save me 4 skill points. unless someone recommends taking 2 more wizard levels, this is at least something.
-Illusion Mastery: ah the big one for me, I can see this one being worthwile if you take signature spell somewhere, but if I do no take that feat is extra spells known (basically save some gold) worth the extra spells per day?

And a question about how echoing spell interacts with earth spell and residual metamagic, is my reasoning correct:
at level 20 I raise a 0th level Silent Image to 9th and gain +9 CL, a turn later I cast an echoing Silent Image again raising a spell with +9 CL because of residual metamagic. This spell returns 4 hours later with -4 CL. I believe this spell will be 20 + 9 - 4 = CL 25. a net gain of 5 CL. 4 hours later I recast this Heigthened Silent Image, applying a free echoing spell, again gaining +9 CL and losing 4CL for a return 4 hours later. This spell would be 25 + 9 - 4 for a CL30. This way I could gain a lot of CL on some of my spells

A friend of mine actually disagrees and tells me it would be (20-4) +9 = Cl 25 for the first return and (20 -4 -4) + 9= CL 21 for the second return, which actually sounds logical but would not be as cool. Since I got an headache thinking about this, could someone help me 

Any help would be appreciated, thanks in advance for any replies.

[sirpercival]

I wouldn't necessarily bother with Echoing spell.  You definitely want Arcane Thesis, Invisible Spell, and Sanctum Spell.  Grab UMD with Naberius and get a wand of Acorn of Far Travel for Sanctum abuse.

A good place for at least 2 of the 3 levels is Escalation Mage -- 2 levels gets you a free 1-level Heighten effect with every casting, which should stack with Heighten Spell and doesn't have the 9th-level cap.

Here's how this works:

1.  To duplicate an Xth-level spell, you need an X+1 level slot as per ScM.
2.  However, with Sanctum Spell and Arcane Thesis, you gain +1 level for a -1 level slot (a net gain of 2 levels), so you only need an X-1 level slot.
3.  Earth Spell grants you an additional level, and making the effect Invisible gets you another level.  That means you need an X-3 level slot.
4.  If you add Escalation Mage in there too, there's another level for an X-4 level slot.

This means that all told you can cast 9th-level spells out of 5th-level slots.  If you want it to be visible, or don't take Escalation mage, that takes a 6th-level slot.  So you can Shadowcraft spells very early.

Another plus is that you can Sanctum-down 6th-level spells so they fit in a Shalantha's Delicate Disk.

Does your DM allow custom items?  If you get 9th-level shadowcrafts to 6th-level slots and take Signature Spell, and you can get a custom item of Mage's Lucubration, you have an arbitrary number of Silent Images to play with.  Simply cast a 6th-level spell once per day (like Superior Resistance or Anticipate Greater Teleport), Sanctum-down'd to 5th level, and then regen it with your custom items as much as you want.  Then you can burn those for Shadowcraft 9th's as often as you want.

Of course, a bunch of this is skirting the line to TO (especially the custom item of Lucubration, which crosses over completely).  However, if you'd really like to see some major ScM shenanigans, feel free to check out Ransom (PM me for questions).

[vhati]

Very interesting, however there are a couple of things that probably wont be allowed by my DM, it is a bit too powerful i am afraid 

escalation mage is alright and very interesting, shows me that I should read more Eberron books

Sanctum spell will probably only work in one specific location and acorn of far travel abuse would not be allowed so its use would be severely limited, becoming a dragonborn and using practical metamagic would probably be more useful i think?

I have asked and arcane thesis would not be allowed to lower level below +0 per metamagic so invisible spell would still be +0 not -1 and since it specifically does not work with heighten spell it cannot be used to lower the adjustment. It would allow me to cast echoing silent image as a 1st level spell, and ring of wizardry I is cheap, werent there some feats that allowed you to break down spell slots?

Custom magic items is a definite no no unfortunately, with enough whining something would probably allowed though but not sure if I want to do that . The shalanta's delicate disks were used to create the cookies with spell thematics right?

It skirts the line to TO a bit too closely, especially since its still supossed to be playable and not too powerful compared to the other players, hence no Arcane Disciple (luck) etc. However Ransom looks totally awesome thanks for the link

ps banned schools are Evocation, Enchantment and Necromancy

[sirpercival]

Why didn't you ban conjuration if you were going into ScM? 

OK, so a lot of that stuff won't work.  Shadowcraft Cookies should still work, though.  You don't need spell thematics (though it's more fun that way).

[vhati]

I did not ban because of teleport spells, planeshift, call kolyarut/zelekhut, and possibly planar binding (even thought I might end up not using this one)

Also I needed to play from level 1 onwards, I put the necromancy and conjuration schools next to each other and I liked conjuration better, I just love the different fog spells and grease etc. Becoming lvl 9 takes a while if you do not play that often.