Spell pen vs spell focus feats

[Jo]

Spell penetration says add +2 lvl to your caster level for defeating spell resistance and spell focus adds +1 bonus to spell DC. Care to discuss what is better for which purpose?

Spells have a maximum caster level so is spell penetration more geared towards people multiclassing that could therefore still reach their max caster level?

[Taebrythn]

both can be needed because if you fail to get passed their spell resistance then it doesn't matter if your dc is high. both become very important to a caster.

[Myriad]

Originally posted by Jo:

Spell penetration says add +2 lvl to your caster level for defeating spell resistance and spell focus adds +1 bonus to spell DC. Care to discuss what is better for which purpose?

Spells have a maximum caster level so is spell penetration more geared towards people multiclassing that could therefore still reach their max caster level?

I'm no expert, but as far as I'm aware, Spell Penetration is used for status affecting spells, like hold or death. And Spell DC is used for damage causing spells like fireball or lightning bolt. One has no (need confirmation) affect on the other, meaning that DC is useless against a death spell, and Penetration is useless against fireball. Although there are spells, which cause both damage and status, that use both.

[CRCGamer]

To the above poster... close but not quite.

Spell penetration is the chance your spell gets past the enemies' spell resistance stat. Which will make any spell fizzle against them. So your hold person, slow, finger of death, etc. All don't even make it to the point they roll a saving throw if it can't get through spell resistance.

Spell DC is basically always important unless the spell is simply fire and forget along the lines of scorching ray where there is no save. Fireball? Save for half damage or if the monster has evasion save to deal no damage. Finger of death? Save against instant death or take a small amount of damage on a save. Most of the spells with no saving throw are pure damage single target in nature.

There are a couple odd exceptions in the mix like Web where running it heightened and with spell focus for the best DC you can get can still screw up high spell resistance encounters like Drow. Where it is indeed a crowd control spell but the spell penetration doesn't apply because it is treated as a physical impediment you conjured into place that the enemy can run into.

And don't multi-class much if at all if you intend to use spells offensively by endgame. These feats that bump up spell penetration values and spell DCs are a "win more" mechanic to tilt the odds further in your favor. But if you need them to even have a chance of working you've messed your build up significantly already.

[Jo]

Thanks CRC Gamer.

If I understand right, as a Favored Soul DPS caster, the spell penetration is not that useful, unlike the spell focus that would make it more difficult for enemies to succeed their saving throw for half damage on my sun bolt and later on, comet?

[Doug]

Originally posted by Jo:

Thanks CRC Gamer.

If I understand right, as a Favored Soul DPS caster, the spell penetration is not that useful, unlike the spell focus that would make it more difficult for enemies to succeed their saving throw for half damage on my sun bolt and later on, comet?

CRC Gamer covered the topic quite well, and you are correct.

If you're a pure DPS caster, you don't need Spell Penetration; it doesn't affect pure damage spells.

Every caster needs all the additions to Spell DCs they can get. If you're a CC (Crowd Control) caster, you first have to make the Spell Penetration check to overcome their Spell Resistance and then the DC check to actually have the spell take effect.

From DDOWiki:

Spell Penetration
------------------
"To affect a creature that has Spell Resistance, you must make a Caster Level Check at least equal to the creature's Spell Resistance:

1d20 + Caster Level + Spell Penetration bonuses (Includes Feats, Enhancements, Epic Destinies, and Items.)

Spell Resistance and Saving throws are separate mechanics. A spell that gets past Spell Resistance may still be saved against.

Caster Level Checks do not automatically succeed on a 20, nor do they automatically fail on a 1."

Spell Focus
------------
When you cast a spell, it has a DC (Difficulty Class) that becomes the saving throw the mob has to make to reduce or eliminate the spell's effect. The mob's saving throw is (just like ours) a 1d20 added to the appropriate base save (Fortitude, Reflex, Will). Obviously, the higher the DC you can attain on spells you cast, the less likely the mob is to save against it.

The equation for your DC is:
"10 + Spell Level + Casting Stat Modifier + Items + Feats + Enhancements + Epic Destiny = DC"

Most spells should show you their DC if you hover over their icon on a shortcut bar. Some SLAs don't; Idk why not.

Note1: These two equations start from a different basis. Neither is based on Character Level.

- Spell Pen is based on Caster Level (Your level in the class that has the spell). Caster Level will equal Character level if you're a pure caster or if the spell is an SLA from a Universal Enhancement or Racial Tree; otherwise it will be Class Level. That means that if you're multiclass, you reduce your Caster Level Checks by 1 for every level taken in another class.

- DCs are based on what level that spell is for that class. For example, "Otto's Sphere of Dancing" is a L7 spell for Wizards and Sorcs, but a L4 spell for Bards. Thus, the bardic version inherently has a lower DC by 3 (unless compensated for in additional bonuses available to Bards that aren't available to Wiz/Sorc). Likewise, the Heighten Feat can only raise the Spell Level to the maximum Spell Level you can cast (L9 for Wiz/Sorc; L6 for Bard, if pure or a small enough 'splash' of multiclass). Thus, multiclassing is more viable for pure DPS casters, because their Spell DCs are only affected by what levels of spells they attain. (A L17 Wizard gets L9 spells, so could take 3 levels in another class without negatively impacting their Spell DCs. OTOH, a Sorc doesn't get L9 spells until L18, and a Bard gets L6 spells at L16.)

Note2: With this information, it is possible to empirically determine the Spell Resistance and Saves of any mob in the game. Since your Spell Pen and Spell DCs can be known and kept constant, simply casting at the same mob over and over and noting how frequently they resist or save against your spells, you can accurately determine their SR and Saves. And this information is listed in DDOWiki for many types of mobs. If you want to know if you're hitting effective Spell Pen and Spell DC numbers, you can either simply see how your own spells do.. or compare your stats to the mobs'.

[Jo]

Thanks Doug! It is all clear now.

[Doug]

Originally posted by Jo:

Thanks Doug! It is all clear now.

One other consideration. Many builds are Feat-starved, so it behooves you to know the full effect of taking or not taking a particular Feat.

Unless they've changed them (I haven't checked lately), many sources of Spell Focus and Spell Penetration in Enhancements or Epic Destinies require you to have taken the initial Feat. They're conceived as building upon the Feat, rather than as alternative sources. So even though, for example, Past Life: Wizard (Active Feat) gives a +1 to all DCs, whereas Spell Focus only gives +1 to a single spell school's DCs, it can be wiser to take the Spell Focus Feat in order to meet the prerequisite for further bonuses in Enhancements and Epic Destinies.

Do check the specifics on the Enhancement Trees and Epic Destinies you plan to take, to see if they're worded so as to require the Feat as a prereq.

(And don't forget the availability of the Past Life: Wizard Feat. It's quite literally the only Active Past Life Feat I've ever taken.. but I take it quite frequently on my casters.)