15th lvl Warlock needs help selecting power!

[Sigdel]

My warlock just hit 15th lvl and I am having a heck of a time selecting his final Greater invocation. Right now he has chilling tentacles and vitriolic blast. I have narrowed my choices to painful slumber of ages and wall of perilous flame.
If anyone has any opinions on these powers of suggestions for other ones I would be very grateful.

 

[Mustrum_Ridcully]

Both sound cool (not as cool as the Chilly Tentacles, but... )

Wall of Fire and the Chilling Tentacles cover the same spot - controlling the area by restricting safe movement for enemies (but they can hinder the party). So, Wall of Fire might not turn out so important for your character, but it offers more overall flexibility. If you have no way of dealing fire damage yet, it is a very useful choice, and its "destruction" effect on burning away opponents is nice, too (even if usually inconsequential).

Painful Slumber is basically a "Save or Die" effect that you can do all the time. Many opponents might turn out immune or very resistant to it, since it's a sleep effect.
With Vitrolic Blast, you bascically have enhanced the utility of your Eldritch Blast that makes it useful against most opponents (assuming that you also have one or two of the shapes of the lover-type invocations).

The risk with Painful Slumber is that it's an all or nothing effect. Eldritch Blast at your level is usually a guaranteed effect, which stacks with your party efforts to take down an opponent. If you have a very high charisma score, Painful Slumber is a good choice. But if you neglected your charisma so far, Painful Slumber forces you to improve it.

 

[Sigdel]

Both sound cool (not as cool as the Chilly Tentacles, but... )

Wall of Fire and the Chilling Tentacles cover the same spot - controlling the area by restricting safe movement for enemies (but they can hinder the party). So, Wall of Fire might not turn out so important for your character, but it offers more overall flexibility. If you have no way of dealing fire damage yet, it is a very useful choice, and its "destruction" effect on burning away opponents is nice, too (even if usually inconsequential).

Painful Slumber is basically a "Save or Die" effect that you can do all the time. Many opponents might turn out immune or very resistant to it, since it's a sleep effect.
With Vitrolic Blast, you bascically have enhanced the utility of your Eldritch Blast that makes it useful against most opponents (assuming that you also have one or two of the shapes of the lover-type invocations).

The risk with Painful Slumber is that it's an all or nothing effect. Eldritch Blast at your level is usually a guaranteed effect, which stacks with your party efforts to take down an opponent. If you have a very high charisma score, Painful Slumber is a good choice. But if you neglected your charisma so far, Painful Slumber forces you to improve it.

Right now my Charisma is 19. So the save for Painful Slumber would be 20, I think. I am just torn between this.
On one hand, Wall o Fire will allow me greater battlefield control. But if used in the wrong situation could end up causing some bad side affects.
Painful slumber, on the other hand, is a instant win if they fail the save. But, like you said, if they are immune than it is useless.

This is not going to be an easy choice.

 

[Mustrum_Ridcully]

What kind of monsters did your character fight most in the past? Or what kind of monsters does he expect to fight in the future?
If you fought mainly Undead, Elementals, Outsiders or Dragons, Painful Slumber doesn't sound so great. If you fought mainly humanoids and expect that to continue, it's a good choice.
Also note that you should be able to dismiss Perilous Flames (if I am not mistaken), so any suboptimal tactical choice can probably be undone, though it will cost you an action)

Does your Warlock have Spell Penetration to get through enemies Spell Resistance? If not, this adds another way to negate Painful Slumber. Wall of Fire will be hurt more, but you get multiple checks against multiple creatures.

A Charisma of 19-20 at level 15 isn't that big, by the way, so it might be best to avoid Painful Slumber. Spellcasters that rely more on their spellcasting ability scores would probably have a value of 22-24 at that point (with magic items), possibly more, and they might also have feats to increase their save DCs higher. (That's not guaranteed, though, it depends a lot on their focus)

 

[isoChron]

Depending on how often magic effects come up in your game (traps, forbiddance, etc.) it may be a good choice to take "Devour Magic".
Sure it's range touch only, but a greater dispel magic as often as you like is a great tool. And it's only depended on your CL not CHA. Even SR does not apply. With time you can dispel everything up to CL 24.

Walls are nice and the no save issue is a big bonus for your low CHA.

So it depends on your Campaign what works best.