Warlock build help

[Sir cryosin]

I was thinking of bulding a roguest warlock I was thinking about taking the invocation were I can cast disguise self at will. Then I'm stuck between agonizing blast or the one where I can cash silent image at will. Background Criminal for sthelth and thieves tools. I'm thinking about fay pack. And when I hit 3rd lv I'm picking tome getting thaumaturgy, guidance, and vicious mockery.

Any advice or input on this build.
Edited: he's a halfling Lightfoot

[Lord Il Palazzo]

How much do you know about the game? If there's going to be a greater focus on roleplay, interaction and exploration over combat, the value of Silent Image goes up a bit. If it's going to be very combat heavy, Agonizing Blast is really, really hard to argue with.

You could compromise, taking Agonizing Blast now and taking Minor Illusion as one of your cantrips. If you get enough use out of it, upgrade to Silent Image next time you get an invocation. If not, Silent Image might not have been a good pick in the first place.

[Sir cryosin]

I have played other characters with 2 lv warlock dips were I had silent image as a invocation and I did some cool things with it in and out of combat dm is not a harsh on illusions. This character is a back up character for death house and then over into ravenloft campaign.

[Corran]

You want a rogue-ish warlock? A rogue dip works perfectly with warlock as your main class. But first let me start from the race.

You are a halfling.That means two things. You are dex based and you lack darkvision. Dex based means your best bet is to stick with a rapier and rely on cantrips such as BB, where melee combat is concerned. Lack of darkvision can be a serious hinderance, which can easily be fixed by selecting the devil's sight invocation. Sooner or later you will take it, and sooner is better than later.

A 2 level rogue dip will give you cunning action. That will help you disengage foes when you want to spam EB, but most importantly, it will allow you to hide when inside magical darkness without sacrificing your action. So you essentially get access to the darkness + devil's sight +cunning action hide combo, which you can utilise either with EB, but even better with BB, since most enemies will choose to move and thus take the secondary damage of BB.
Besides, a rogue dip will give you one extra skill and thieves' tool proficiency, besides all the other benefits (cunning action, expertise, etc). Really recommend it.

As for mask of many faces, the best way to exploit and roleplay it, is to take the actor feat and the cantrip friends. The actor feat will allow you to assume the voice of the person you are impersonating, and the advantage on social skills will minimize the investigation checks against your guise. Besides, the advantage on social skills, along with the expertise in 2 skills and 1 extra skill from rogue will make you a very decent skill monkey. Friends with unlimited disguise self is also rather fun too.

[Lord Il Palazzo]

I have played other characters with 2 lv warlock dips were I had silent image as a invocation and I did some cool things with it in and out of combat dm is not a harsh on illusions. This character is a back up character for death house and then over into ravenloft campaign.If it's a backup character, you could leave it ambiguous until you see what the party's like and pick when/if you need to use the character. If the party's low on damage output or already has an illusionist, pick up Agonizing Blast, if you think you'd get a lot of use out of Silent Image, pick that up.

I briefly played a warlock with Misty Visions (I think that's the Silent Image invocation's name) and had a great time with it. It's definitely the more fun (if less optimized) pick.