Since your build won't work well without good end gear anyway, I suggest you make the build assuming that you will get all the gear you need in the near future (ex. exceptional stats).
I suggest going like this.
Starting stats
Max con and cha, dump all else in int.
Use bull's strength wands and carry lesser resto pots while leveling up.
Skills
Max out concentration and UMD on every level up
Feats
Your Current- Toughness
- Extend
- Force of Personality -> Heighten (20)
- Maximize
- SF: Necro
- SF: Evoc
- GSF: Necro
- Empower
Suggestion- Toughness
- Empower
- Past Life: Sorc -> Spell Penetration (20)
- Maximize
- SF: Evoc
- SF: Necro
- Heighten
- GSF: Necro
DCs
Aim for 40 base cha
18 - base
05 - level ups
07 - item (preferably Epic Helm of Frost)
02 - exc +2 (ToD ring)
01 - exc +1 (ToD ring or epic augment)
03 - sorc enhancements
01 - human enhancement
01 - litany of the dead trinket
02 - +2 tome
----
40 - total unbuffed cha
02 - yugo pot
02 - ship buff
----
44 - 17 cha mod*
Necro DC:
10 - base
09 - spell level
17 - cha mod
02 - item
01 - SF: necro
01 - GSF: necro
----
40 - Necromancy DC
Evoc DC:
10 - base
09 - spell level
17 - cha mod
02 - item
01 - SF: evoc
01 - passive sorc PL
----
40 - Evocation DC
* Can push cha mod to 18, and effectively DCs to 41 if you obtain a +4 tome.
Cheers.