feedback on this tree has been very negative from what i've seen, it doesnt do nearly as much dmg as other builds (warlock in general has a problem with dps, but this seems bad even for a warlock), and the small amount of Crowd Control it does makes enemies scatter, which will usually hurt a team more than helping it. Usually i try to go for one or 2 small changes that have large effects on the playstyle. might need to bump it up a bit for this one but i'll try to keep it manageable...
1. Blast shape beam should be changed to a small, long-range cone like scorch that can hit multiple enemies long range as well as smaller enemies. beam shape as is just isnt working, no one's using it. There's already much better long-range single-target options, and much better AoE options. There's no reason to pick it. If this was changed to an actual AoE long range beam instead of the tiny targeting it has, then it would actually fill a useful new attack for a warlock.
2. Fiendish Glare and Glare of the Pit should have the fear effect changed to a different kind of fear effect that paralyzes enemies for like 1.5 secs. short enough so that "CC chars" will still be much more useful for CC, but long enough to help out a little bit solo and maybe even work well with a CC char by being able to fill any short gaps that pop up, or paralyze the first group of enemies for a few secs till the other enemies get there at which point the CC char can hit them easier all at once. this char needs to work well with a party, not against it. not quite sure how it works now since there's no info on it, but i think the fear effect on both of these skills should be a separate necromancy save DC
3. Drink their Fear should be changed to have your fear-like spells and SLAs (including Fiendish glare and Glare of the pit) apply a "mark" on the target that lasts several seconds and is separate from the actual fear, and that can target bosses. creatures with that mark should take double pact damage, or if they're immune to fire, they lose their fire immunity instead for the duration of the mark. warlocks need a way to remove immunity, and to deal better dmg to bosses. this would help with both of those. This way they'll still deal less dmg to enemies that were immune to fire too, so it's not too good.
4. Fiendish Symbiosis should be changed to permanent toggle for a short range melee aoe blast. maybe lower the fort bonus and take out the healed by fire part to compensate. If this warlock is going to be a melee caster it's gotta actually be able to use melee when it needs to, and ranged when it needs to. If a long-range sorc blaster is still going to be able to out damage a melee in it's special transformed form that it can only do 1/3 of the time, you should at least be able to make the change permanent. Eldritch Knights already have good long-range spells with good close-range attacks and spells too. This warlock needs to be able to compete with those chars, so give it a hard-hitting melee aoe main attack so that it can do good melee dmg when it needs to. maybe even increase the spell dmg bonus to like 225% or even 250% since feedback on dmg for this skill has been really bad so far.
This tree already has nice defenses for a caster, and that should enable it to be an effective short-range dps caster with some smaller long range aoe dmg. and if it's not going to be able to compete with a sorc for dmg, or a wizard for DCs and versatility, it should at least have melee aoe dps that is at least close to a sorc's aoe dps, while throwing in a little bit of USEFUL CC that can work well solo or in a group.
Thank you for your time, i hope this helps.