Spoiler: Ranged dpr
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With a paladin, bard, monk and rogue as allies, the party's range dpr is most likely not all that amazing (or am I wrong?), so boosting your single target range damage a little would be a decent thing to do. Being a shadow sorcerer means a darkvision range of 120', which is enough to give yourself sight superiority against plenty of things under the right conditions. So this 120' of darkvision will sometimes translate to advantage on your ranged attacks (provided you attack from outside your target's sight, so further from their darkvision range and away from light sources). Having this potential advantage, you now only need a way to bring up the damage, given of course that it will be a spell with a big enough range (120' range to match your darkvision isprobably ideal). I'd grab scorching ray for that, unless your DM rules that because it is a collection if fire rays they cancel the advantage, either because they produce enough light (to briefly reveal your position) or because the enemy seeing the rays coming at them is enough to cancel the advantage you have from being an unseen attacker (the latter not being RAW if I am not horribly mistaken, but not too much of an unlikely DM ruling I would say). So yeah, scorching ray if your DM rules that using it dos not reveal your position when attacking (much like crown of stars actually does). Next levels when your cantrips power up I would confidentally drop scorching ray and I would rely on a long range attack cantrip for dpr (so chill touch, with firebolt as an alternative if your campaign has an unusual amount of necrotic resistant cratures). I might be tempted to pick up scorching ray once again at the very high levels if I ended up with quicken as one of my last metamagic choices.
Edit: Another way to boost your party's dpr is to grab haste and use it on the rogue (since they are the main ranged dpr, as this can double their damage output during a round).


Spoiler: Hound of ill omen and single target save or suck
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Next, the hound. It bestows disadvnatage on an enemy save. Any save or suck spell will work well with it, but the spells that work best with the hound are the single target save or suck spells (though you might want to pick up something like toll the dead for better odds at spamming some damage when the hound is around). Best single target save or suck spells? I'll get back to that. First, the cost. Using the hound is expenssive, so avoid expenssive metamagic options unless they are too good not to have. That's for example why in the ending of the above paragraph I was operating under the assumption that quicken is not to be picked unless possibly at the very high levels. Because quicken tends to burn through sorcerer points fast, and with the hound on top of your other metamagic uses you wont have too many points to spare. Let's go back to the best single target save or suck spells that your hound can let you make the most of. I'd suggest starting a thead about this, cause I wont remember every single one. Some good ones though are the following: tasha's hiddeous laughter, levitate, suggestion, hold person/monster, dominate person/ monster, polymorph, plane shift (assuming you hit with an attack; anything that gets you advantage or a flat attack bonus combines nicely here, so stuff like your origin's darkness, invisibilty, soul cage, etc), banishment, Otiluke's resilient sphere, etc. Notice that most of these spell suffer some restriction (eg hiddeous laughter wont work on anything that is immune to being prone or with a very low INT score; hold/dominate person is restricted to humanois, levitate is restricted by enemy weight, resilient sphere is restricted by enemy size, plane shift requires you to land a hit, etc). Banishment is a good save or suck, but a lot of its value comes down to being able to upcast it and include additional targets, which does not combine all the perfectly with your hound of ill omen. But polymorph, polymorph does not suffer any other limitation other than the enemy failing its save. It's not possible to upcast it, which does not matter when we are talking about its synergy with hound of ill omen, and it makes up for not being upcastable by having a stronger effect when for example we compare it to banishment. In fact its effect is incredibly strong it you try to exploit it, say by having a bag of devouring around, but there are other ways as well (IIRC drowning still kills the creature rather than dropping its HP to 0, so having it revert to its natural form). So yeah, I'd grab polymorph for sure, and I make sure to use it with the hound when there is a noticeably strong non legendary creature around.


Spoiler: Nova potential
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With polymorph being a given for me, I might consider twinned. Hound of ill omen + twinned polymorph (probably splitting this into a debuff and a buff at mid levels) will eat away at almost all your sp initial budget, but I like having burst just in case I might ever need to use it, even though it would probably take a very dire situation for me to consider throwing that many sp away together at one go. Still, I would like having the option, so I'd grab twinned.


Spoiler: Twinned buffing potential relies on group tactics
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Having the twinned metamagic opens widely the route of buffing, and you've got allies that could potentially make good use of the buffing spells that are good candidates for twinned (mainly haste and greater invisibility). Haste is particularly good on a rogue as mentioned previously, greater invisibility is excellent for a melee rogue and it can be good for any pc that has either a good base AC or a good return on damage vs accuracy boost (so typicallY GWMs and SSs), even more so if a pc combines both these two so that with invisibility on they would greatly benefit both defensively and offensively. Here is the issue though. The hound puts too much stress in your sorcery points, and besides polymorph and potentially haste, you will have enough concentration spells after we touch on AoE candidates. So further investing in twinned buffing (say for example by grabbing both haste and greater invisibility) might not be a good idea. Only do it if it can offer you something great in term of party tactics. Ie, only use twinned haste or grab greater invisibility and go for a twinned version of it, only when doing so helps you tremendously winning a fight. How would such a twinned buffing help you tremendously in winning a fight? When it's used as the core of your party tactics. Example, you use greater invisibility on the rogue and on the high AC paladin while you and the bard are on top of the bard's find (greater) steed and away from danger. This can win you a fight against the toughest melee enemies without special senses to pierce through invisibility. Or use haste on the rogue and on the monk who will kite enemies along with the mounted paladin while you and the bard use ranged attacks from a safe distance (while having options to reposition to safety should anything threaten you). Etc. If you can use a twinned haste or grater invisibility like that, then it's worth it. Otherwise you might want to pick up haste just for buffing the rogue's range dpr should you ever need it, and polymorph to use with hound of ill omen, with twinned acting as a great thing to have should you ever need it, and not as something that is one of your go-to options.


Spoiler: Go for cheap metamagic options
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Before going any further, apart from twinned I would go for cheap metamagic options for my other choices. I'll mention careful and empower briefly in the next paragraph which will be about AoE's, so here I'll touch on subtle. Combat wise it will give you the edge in fights where the enemy has casters (even moreso if said casters have access to counterspell). Out of combat it combines decently with some spells, most notably IME with dtect thouhts and suggestion (but there are other candidates that if paired with subtle can create for some funny situations).



Spoiler: AoE's
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Let's talk AoE's.

Spoiler: Fireball
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First, you need damage AoE's. Two of them at least to differentiate damage type, or just go for a fireball and pick the metamagic that allows you to change the damage type (haven't put much thought what's of these two is worth more). You need damage AoE since your group is lacking, but that's just the main incentive. You have a little more incentive because you have a rogue and a monk in the party. These guys get evasion. Which means, that you can have at least one of them act as bait, gather lots of enemies around them, and then you drop the AoE. This is one case where investing in both careful and empower and using them with the same damage AoE could be very beneficial, provided that the rogue and/or the monk caught lots of fishes that were willing to surround them. Even with neither careful and empower this is something you will want to attempt when you have the chance, but careful can mitigate the risk considerably and empower will allow a good bonus buff for its cost if your targets are many.

Spoiler: Fear
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Let's now talk about concentration AoEs. In this party this is going to be your main contribution (unless you manage to make the best out of twinned buffing via group tactics), with hound + polymorph and ranged dpr being more of a secondary role for you. You've got a bard in the team so it would be best if you can share the burden/glory (thus allowing you to either economize resources or focus on one of your secondary roles when they lead with a concentration AoE). Let's look at good spell candidates for this role. To know which spells are good, you first need to look to your allies. What do you see? I see a paladin with aura of courage. This means that when the enemies fight say, the paladin, the rogue and the monk in the front lines, and they are all buched up together, then you will be able to throw the fear spell, affecting all the enemies that are nicely lined up around your melee allies, while not affecting any of your allies if they are within 10' of the paladin. And you dont even need careful for that, it's party friendly already thanks to the paladin's aura. Party friendly is a big deal when it comes to AoEs, because it means you can rely on them more often and because it means you turn placement restrictions into placement opportunities, thus profiting enormously in situations like the one I described above. But that's not all when it comes to party friendly fear spell in this party. Do you know how enemies affected by the fear spell spend their turns? They dash away. Which means opportunity attacks. You've got a rogue, and rogues have the strongest OA in the game when it comes to pcs. You've got a paladin who as well have a pretty decent OA given their IDS. And you've got a monk, who can stunning strike with their OAs, thus potentially locking a target in place, which means yet another turn of OAs attacks from the rogue and from the paladin along with yet one more wasted turn from one of your enemies. Combos do get better than that, but that's plenty good I would say.

Spoiler: Extra
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So yeah, fear and fireball will allow you to get very good value out of them because of the need for AoEs in your party but also because of how these AoEs synergize with your allies' abilities. In summation, you will want to back up fireball with something, which would be at least one more AoE of different damage type or the metamagic that allows you to change the damage type (pick what you think is best) and maybe even with either of or both of careful and empower. And you will probably want to back up fear with something like careful confusion (that is without additional restrictions in a similar way that polymorph is when I was talking about single target save or suck spells).


Fill the rest of your spell picks with defense and mobility options, along with any utility that sounds useful for your campaign or nice for your character to have.