What enhancements contribute to Finger of Death and Phantasmal Killer?

[praetor]

Just need some help planning my enhancements. What enhancements provide benefits to Finger of Death and Phantasmal Killer?

Specifically, how can I improve their success rate?

[Adoraro]

Charisma (DCs) and Spell Penetration (Penetrating Spell resistance).

[BalanceFx]

FoD is Necromancy based. So Necromancy Focus.
PK is Illusion based so Illusion focus.

Phantasmal Killer has two saves to Work... FoD has just one.

[PSU93]

In addition to Enhancements, there are Feats and Items that will help with success as well.

Spell Penetration increases your DC to see if the spell "hits."
Spell Focus of the appropriate school (i.e., FoD = Necromancy) makes it harder for the mob to Save against the spell.

Spell Pen and Spell Focus bonuses from Feats stack with bonuses from Items, and obviously Enhancements do too.

[praetor]

What is the mechanism of focus -- that is how does it make it harder for enemies to save against it?

How does it differ from spell penetration?

Is spell pen applied first to see if it hits, then spell focus to see if the enemy resists?

Most importantly, do any of the Spell Damage Amplification enhancements contribute to FoD or PK? I am referring to Force & Repair, Fire & Cold, Acid & Electric lines: http://ddowiki.com/page/Sorcerer_enhancements

[arcticwolf666]

FoD is Necromancy based. So Necromancy Focus.
PK is Illusion based so Illusion focus.

Phantasmal Killer has two saves to Work... FoD has just one.

Yep, and PK is illusion and necromancy whilst FOD is necromancy only

[flynnjsw]

What is the mechanism of focus -- that is how does it make it harder for enemies to save against it?

How does it differ from spell penetration?

Is spell pen applied first to see if it hits, then spell focus to see if the enemy resists?
Yes, if a creature has SR, then you have to overcome the SR before the creature has to make a save
Most importantly, do any of the Spell Damage Amplification enhancements contribute to FoD or PK? No, because they are none of the above. I am referring to Force & Repair, Fire & Cold, Acid & Electric lines: http://ddowiki.com/page/Sorcerer_enhancements

Answers in red.