Hi everyone,

as many other people I know, I have this thing when I want to use my Fiend Chainlock to deal as much damage as possible in a battle because that way I feel most useful and accomplished. This is why I mostly pick offensive spells and cantrips every time I level up and as a consequence I ended up with a lot of damage dealing spells but only a very few utility/RP/control spells. At the same time, however, I realize that being able to control the battlefield or assist in ways other than dealing damage is often more helpful for the group, especially given the fact that we already have a good sorcerer who does a lot of damage anyway. It became even clearer to me the last session when we encountered some vampires and we were supposed to actually capture them, not kill them. It was a sub-mission so it did not include our entire usual party, just me, the mentioned sorcerer and a bard. I managed to pull of some nice tricks with my Ascendant Step invocation and essentially became a tank for this mission as the least squishy character, but the sorcerer did an excellent job by animating nets and ropes we were given to restrain and capture the vampires while being assisted by the bard who cast many useful support spells.

Point is, my warlock is very good at dealing damage (he holds several damage-related records that our DM keeps track of) but sucks at improvising or being able to do useful tricks when damage is not what you want and often our DM indeed comes up with such scenarios. Therefore, here is the list of cantrips and spells I can cast and I would love to hear your opinions, for example if you would get rid of some of those spells and swap it for something else. Thanks heaps!

Cantrips: Eldtrich Blast (obviously a must); Chill Touch; Frostbite; Prestidigitation (the only RP/utility cantrip with limited combat use that I have because it is an extra cantrip I got as a high elf).

Spells: Levitate (at will because of the Ascendant Step invocation - super fun and creative); Misty Step (can only cast once per short rest since I picked the Fey Teleportation feat but I love the fact that I can escape without using a spell slot); Blight; Counterspell; Enervation; Find Familiar (Pact of Chain); Fireball; Hellish Rebuke; Mirror Image; Scorching Ray; Summon Greater Demon; Synaptic Static; Wall of Fire.

With just 2 spell slots (3 slots starting at 11th level) and two more casters in your party I would certainly swap counterspell.  Let the others use a spell slot on it. Blight and Mirror Image seems redundant, drop one of them. Again, Hellish Rebuke with just 2 spell slots seems a waste. When you can get it as a racial feature, that is a complete different story. Then there is Scorching Ray, shouldn‘t Eldritch Blast be enough?

I would take Dispel Magic instead of Counterspell and then take something like Scrying, Invisibility (that is so useful and works on 3 more party members as well!), and maybe Dimension Door or look at Suggestion (or Command as fiendlock).

You like Ascendent Step, but remember that with Fly as a 5th level spell not only you but 2 more party member can, well, fly. I would take Mask of Many Faces (unlimited Disguise Self is really usefull) or Misty Visions as Invocation for the utility instead. Also get Polymorph with the Sculptor of Flesh Invocation. Maybe Whispers of the Grave? Adventurers tend to find a lot of dead bodies.

Edit: I forgot the Cantrips: Minor Illusion is IMHO the most versatile cantrip, followed by Mage Hand. 
That is a lot to swap, hope you can arrange something with your DM…

I would let the full casters handle counterspell/dispel magic.  While really impactful, with only 2 slots those aren't your best options.

One simple one to consider is Hold Person. With things upcasting to 5th level you will now be affecting a ton of humanoids with the spell.  Fly and invisibility upcasting can be huge improvements to the party.  The illusion spells are also interesting, but you have to like working with them (and your DM has to be accommodating or they are useless).

I actually like how scorching ray fits in there.  You have a couple of spell pairs that I would consider dropping on of the pair Blight/Enervation and Fireball/Synaptic Static.  I dislike Summon Greater Demon so would swap that out.  I prefer the more reliable Summon Shadowspawn.

On the invocation front, Sculptor of Flesh is super versatile, offensive (turn ally into giant ape), defensive (turn enemy into a frog), and temp healing (turn ally into giant ape).  I would be interested to hear how you used levitate creatively. 

Thanks for the advice guys, I agree with the Counterspell, there was only like a single instance when both me and the sorcerer had to use it. I was definitely going to get Fly, but still want to keep the Ascendant Step because casting levitate unlimited amount of times is just super cool, it proved highly useful in and out of combat. I agree that Invisibility is great, I was looking at the invocation that grants this at will but it is level 15 so still a long way to go. Dispel Magic sounds good and so does the Sculptor of Flesh, I will consider both. Dimension Door and Hold Person are also interesting options, thanks for that! I will drop Scorching Ray indeed because I have so many fire spells already and tbh I used this spell like twice in total. When it comes to Blight, Enervation, Fireball and Synaptic Static, I have my campaign-specific reasons to have those so I will keep them. Brilliant advice, thanks!