A blaster does not need high DCs.
Depending on your build, you should consider the following. Apotential build can be Sorc10/Asoc10/AM10. If you dont mind being Evil, at least 6levels of Bloodmagus can help a lot. 7 levels of palemaster instead, if you need AC and Defences
- Take AM at least to level 8 - Master of elements will enable to switch the energy type of darts, icestorms, flame arrows etc.
- Mastery of shaping can help especially if you plan to party AND care about the party members

- If your build gets CL30 then you are good. You can spend the rest of High Arcanas for SLAs. Those can be either the Bigby spells ( if they are fixed ), buffs or Santuary. If not CL30 use high Arcanas for spell power.
- Get at least one damaging spell on each level. This is important
- Get ASoC. It is a must for a blaster
- Target for CHA28 for the extra level9 spell. Base25 +3Item. If you can make it higher, even better.
The spell selection can look like this
1. Expeditious Retreat, Grease, Orb of Fire, Protection From Alignment, Ray of Enfeeblement
2. Blindsight, Cats Grace, Ice Darts, Bears Endurance, Mirror Image
3. Impr. Mage Armor, Flame Arrow, Haste, Vampiric tpuch
4. Wall of fire, Greater Invisibility, Orb of fire, Ice Storm or enervation
5. Cloudkill, Lesser Spell Mantle, Greater Fireburst, Mind Blank
6. Bigby 6, Gr Missile Storm, Gr. Heroism
7. Avasculate, Energy Immunity, Shadow Shield
8. Polar Ray, Premonition, Horrid Wiltigs
9. Bigby's Crushing Hand, Mordenkainen's Disjunction, Wail of the Banshee
Notes.
- You can see at level 9 you can get Gr. Sanctiary for SLA. You can skip that and use boots of etherealness instead.
- If the bigbys are fixed they are good for SLAs, especially Bigby 9 since you need bigby6 as you can quicken it.
- Most of the spells, on every level, you can choose the energy type. So you can use fire against Frost Giants, Cold against Fire Giants etc.
- Spells like Wall fire are great for doing damage in time, especially if your target is pinned down ( bigby 9 )
- You can skip Horrid wiltigs and take Create Gr. Undead if you need a summon and are evil