Necromancer build

[Fae]

I have not played in a while but wanted to make a human wizard necromancer incantatrix who specializes in rays for necromancy i plan to mainly debuff and control rather then raise dead and will be dropping evocation conjuration and enchanting schools of magic but would like help on what feats spells and or classes i should dip into

[Inevitability]

The best wizard races are and will always be human + strongheart halfling, because feats are insane. There's a few races that give +2 intelligence, which is kind of neat if you're going to be forcing saves as often as a debuffer, but in general: human or strongheart halfling is best.

Fell Drain is a pretty good metamagic feat that'll synergize great with necromancy and incantatrix. Fell Frighten is pretty on-theme as well. Other solid options are empower, maximize, QUICKEN, and of course Twin/Repeat at later levels.

Are you set on dropping conjuration? It's one of the most versatile and multifaceted schools. Is it really more valuable to you than something like illusion, which high-level monsters regularly negate with one of their passive abilities?

Master Specialist is a solid PrC that gives some okay benefits and can be entered easily and early, though its 4th-level feature kind of assumes you'll be raising undead. Wizard 3/Master Specialist 2/Incantatrix 10/Master Specialist +5 is a fine build for the kind of character you want to make, if not the most optimized. Alternatively, just go into Master Specialist for a few levels and use the free Skill Focus to enter Archmage or Initiate Of The Sevenfold Veil later.

[Paragon]

While Inevitability covered the usual OP classes, I would think that Spellwarp Sniper matches what you want.
Add Split Ray into the mix, Mobile Spellcasting and I've recently heard of a halfling race that had -10 instead of the usual -20 to hide after sniping (if that's your goal).

[Maat Mons]

Since you expressed an interest in control spells, it may be worth noting that banning Conjuration means giving up Grease, Obscuring Mist, Fog Cloud, Web, Sleet Storm, Stinking Cloud, Black Tentacles, Solid Fog, Cloud Kill, Wall of Stone, Acid Fog, and Wall of Iron, while banning Evocation means giving up Flaming Sphere, Wind Wall, Resilient Sphere, Wall of Fire, Wall of Ice, Wall of Force, Forcecage, and Telekinetic Sphere.

[Biggus]

Add Split Ray into the mix, Mobile Spellcasting and I've recently heard of a halfling race that had -10 instead of the usual -20 to hide after sniping (if that's your goal).

I've heard of feats that reduce the penalty but not a race, what is it please?

[Fae]

I had someon tell me dread necromancer might help too would wizard3/masterspecialist2/spellwarpsniper4/spelltheif1/incantatrix5/dreadnecromancer5 be viable? And no i didnt think about that i just liked illusion spells but if conjuration is that good to help with more debuff and other things then i can get rid of illusion instead i don't really care about raising dead aspects of necromancy

[Inevitability]

I had someon tell me dread necromancer might help too would wizard3/masterspecialist2/spellwarpsniper4/spelltheif1/incantatrix5/dreadnecromancer5 be viable? And no i didnt think about that i just liked illusion spells but if conjuration is that good to help with more debuff and other things then i can get rid of illusion instead i don't really care about raising dead aspects of necromancy

Spellthief and Dread Necromancer are doing very little here, and generally unless you want to theurge it's a bad idea to mix casting classes.

If you're casting as a level 10 wizard and you take five more levels of wizard, you go from 5th to 8th-level spells, unlocking powerful tools like Mind Blank, Maze, Clone, or Polymorph Any Object. Even if you're just looking for debuffs, you get stuff like Greater Dispel Magic, Insanity, Reverse Gravity, or Power Word Blind.

If you are casting as a level 10 wizard and take five levels of dread necromancer, you get... a couple of 1st- and 2nd-level spells per day, most of which you could already cast, and a bunch of abilities that are inferior to a mid/high-level wizard's spells. A negative energy burst that deals 5d4 damage just isn't very impressive when you could instead have increased the damage of Cone Of Cold (which is, mind you, a bad spell) from 10d6 to 15d6.

[Asmotherion]

If I can give a good advice is "Never drop Conjuration".

There is a ton of useful spells in conjuration, and you can make use of Summon Undead line to summon some Allips or other things that deal Ability Score Drain/Damage.

[Fae]

I was honestly only thinking spell theif for the requirement of sneak attack for spellwarp sniper

[ShurikVch]

Since you want to go the "debuffing" route rather than "master of undead" - how about the Master of Curses PrC (Champions of Darkness)?
Sure, BAB +5 requirement don't allow to qualify earlier, and feat requirements are rather "meh!" (one is Skill Focus, and other is based on Ravenloft-specific mechanic of crafting curses), but all this aside - PrC is rather OK:
1. It's a short PrC - only five levels (and you, likely, wouldn't want the capstone - thus, 4 levels)
2. It grants full (5/5) spell progression (and, if it matter, full BAB - for some reason)
3. Curse domain: this prestige domain includes such spells as Doom, Bestow Curse (one level earlier than Wizard), and Harm. Other spells are either less useful (like Poison), from dropped schools (Hold Person - one level earlier than Wizard), or already available to Wizard (Horrid Wilting, Energy Drain). Domain granted power gives +4 to save DC of your Bestow Curse, and allow to cast Mark of Justice 1/day
4. "Vision of Darkness" - it allow, by looking into the target's eyes, learn their "weak spots" (in Ravenloft it helps with crafting curses, but even outside Ravenloft - may help in combat or investigation)
5. Turn or Rebuke Cursed Undead - like a Cleric of your character level, but only on Undead which exist because of a curse

[Fae]

I can't remember is there a chronomancy prc

[Inevitability]

I was honestly only thinking spell theif for the requirement of sneak attack for spellwarp sniper

Ah, my bad. Still, in that case I think Rogue is a better way to get sneak attack than spellthief: it gives more skill points, boosts a saving throw that's more useful for wizards (Reflex instead of Will), and gets you Trapfinding instead of the ability to steal very low-level spells. Maybe if you take Master Spellthief you could make Steal Spell worthwhile, but even then I think traps are more common than arcane casters.

[ShurikVch]

How about the Fearsome Necromancy feat (Complete Mage)?
I mean - it's not a metamagic - it automatically applies to all of your Necromancy spells which allow saving throw; and it - by itself - don't allow saving throw: even if enemy successfully saved against your spell - they're still shaken (if not immune to fear of mind-affecting)
And you, being a Necromancer, can even take it as a Wizard Bonus Feat

[Asmotherion]

I can't remember is there a chronomancy prc

I am not aware of a Chronomancy PrC. But all you need to do is focus on spells like Haste/Slow/Time Stop and the Celerity line of spells to effectivelly create a Time Mage.

Don't forget to grab the Quick Recovery feat from Lords of Madness, to counter the drawbacks of casting Celerity. Find a way of your choice to have a high Will save to always succeed the Save (Since you're Incatatrix, I suggest to Persist Spell: Ruin Delver's Fortune).

There you go, now you have Time on your side.

[Paragon]

I've heard of feats that reduce the penalty but not a race, what is it please?

I was thinking of the kender race from DLCS but it's the halfling rogue sub level that gives that reduction