Optimizing my Jack of All Trades Warlock

[Mythalidor]

I have a game coming up, where I am trying to create a versatile character, while not giving up on too much power. Right now, I'm planning it as a Half-Elf Rogue, to get 8 starting proficiencies, then multiclassing into a Lore Bard to get more skill proficiencies. Then to Pact of the Blade Warlock.
My goal is to have most of my damage coming from the Pact Weapon with spells like Booming Blade, while the rest of my spells go to utility rather than damage. Any suggestions people have are welcome, all modules and U.A. are welcome.
My current idea is:
Half-Elf Sage. At least Rogue 1/Lore Bard 3/Hexlock 3. So it has 14 skill proficiencies (Beguling Influence Invocation), uses its pact weapon as its spellcasting focus (Improved Pact Weapon) then a shield in its offhand.
The point of the character is to be able to support almost any party composition, be melee for a group of magicians, be magic for a group of fighters. I was thinking of leveling Lore Bard to 14 for magical secrets and a level 7 spell slot for Magnificient Mansion or other utility spells, but I am not sure what would be best.

[Keravath]

Starting rogue will maximize your skills since you will pick up another when you MC into bard.

8 + 1 + 3 for level 3 lore bard. 12 skills with expertise in 4. I'm not sure I would go with the warlock invocation for the social skills since they can be useful from the beginning and you will have to wait until a minimum of level 3 but probably higher (if you don't immediately do the hexblade multiclass).

If you go to level three in rogue Scout you will also pick up expertise in both Nature and Survival.
Knowledge cleric can also give expertise in two knowledge skills as well as the guidance cantrip.

A lot depends on how much you want to be good at skills vs everything else.

From a damage perspective, two levels of hexblade warlock gives you eldritch+agonizing blast which may be a bit boring but supplies fairly reliable and scalable ranged damage ability especially if combined with hex (and you aren't using concentration for something better).

Level 3 spells at 5th level and the level 6lvl magical secrets are important levels for a bard. These get pushed off to a minimum of 6/7 if you just do rogue first or 8/9 if you do two levels of warlock (9/10 if you do three levels of warlock before going back to bard).

One thing to keep in mind is that you won't be keeping up with melee damage. Thirsting blade requires level 5 of warlock (and blade pact) for extra attack. Without extra attack, the one melee attack/turn even with booming blade doesn't compare well to eldritch blast. (d8+cha + d8 (+possible d8 if they move)) vs (d10+cha + d10+cha) (at level 5-10). You are also a lot more vulnerable if at melee range and it makes it more difficult for you to reliably keep up concentration spells.

Bards have a limited selection of spells but they can be very effective at helping to control the battle and aiding your team ..
Healing Word
Faerie Fire
Dissonant Whispers
Blindness/Deafness
Shatter
Phantasmal Force
Hypnotic Pattern
.. are all good choices. There are also a wide choice of magical secrets at level 6 lore bard ... with fireball and counterspell being common choices.

However, you may feel underpowered at level 5 when the others in your party pick up level 3 spells and extra attack. I have a level 6 lore bard/2 hexblade warlock and eldritch+agonizing blast was very useful through levels 5 and 6 since it kept the character's ability to do damage relevant.

Other's might have a different opinion ... but I would suggest leveling either as:
1 rogue -> 6 bard -> 2 warlock ... which gets the bard spells on line as early as possible
or
1 rogue -> 2 warlock -> 6 bard ... which delays the bard spells, and additional skills but picks up the warlock utility features, proficiencies (shield/med armor/martial weapons),spells (hex and shield), invocations (agonizing blast + 1), hex warrior, booming blade cantrip and eldritch blast cantrip, hexblade's curse.

Lots of tradeoffs on how to build the character that you will find fun to use as you level up as well as being able to contribute.

[Mythalidor]

Thanks Keravath, I probably should have mentioned that my DM generally ignores the Nature, Survival, and Religion skills, so proficiency in 15 skills would cover all that are in an average campaign with them, so having the 14 from before is close enough, I know I could use the skilled feat, to get the last skill, in place of the Beguiling Influence Invocation, but I wasn't sure if it was better to save an ASI or and Invocation.
What you mentioned about Eldritch Blast versus the Pact Blade was a good point, I had forgotten that Eldritch Blast continued scaling per level, so I will likely switch the character to that.
If I switch to Eldritch Blast, would it be better to switch my pact to chain or tome in order to gain more versatility, or to stay with the blade?

[Keravath]

Tome is nice for the ritual casting and the ability to get all the ritual spells up to second level. You can also pick up the Find Familiar ritual and 3 cantrips when you get it which will give you a regular familiar like a owl.

The regular familiars aren't as good as the special warlock ones but the only real thing they are missing is the invisibility feature. An owl familiar has the flyby ability which allows it to use the help action on a target and then move out of range without taking an attack of opportunity which is an ability provided by the invisible familiars unless your DM rules that using the help action makes them visible (as far as I know this is not how it works in RAW) but this would make the owl actually better for using the help action.

The invisible familiars can be very useful in some scouting situations as well though much of the time a regular familiar can do almost as well.

Blade pact is somewhat niche in that it focuses on weapon use ... melee weapons unless you take the improved pact weapon invocation. One item I overlooked is that your 1 level of rogue does give a 1d6 sneak attack bonus die which can also be added to your melee damage if you use either the attack action or cast booming blade and your pact weapon is a finesse weapon. Sneak attack would also work with a bow or crossbow but does not work with eldritch blast.

In the long run, if there is any chance your game might run to level 20, you might want to only spend 2 levels in warlock since otherwise you will be giving up 9th level spells at level 20 which might be a consideration.

Even without that, I would still tend to take only a couple of levels of warlock before building up the bard levels quite a bit ... then take additional warlock levels later if you like as you see how the character develops. Two warlock levels gives you most of what you are looking for but if you find that you could really use the features of one of the warlock pacts later on then you can choose then.

--------

In terms of ASI progression you may want to focus on charisma at first rather than feats. Charisma affects attack and damage bonus with both spells and cantrips as well as your spell DC and your ability with the social skills (persuasion, deception, intimidation, performance) so I would think that your first two ASIs will likely be used to raise your charisma from 16 to 20.

However, the build is really only dependent on charisma so after reaching 20 you can probably pick and choose which feats or stat boosts you might like for the rest of the ASIs.