1st Level: Eyes of the Dark and Strength of the Grave
Eyes of the Dark is the core build-around feature this option leans on. 2 sorcery points for a 2nd level spell slot is a decent rate, as they’d normally cost 3, and when you cast Darkness with this, you can see through it. Seeing through magical darkness sets you up to take advantage of enemies suffering from fighting in Heavy Obscurity while you suffer no such penalty.
You can slap this down on yourself at the start of a fight and leverage the given 120 ft. darkvision to see out of this and fire off spell attack rolls with advantage, as you’re an unseen attacker to anything without Devil’s Sight outside your pool. This additionally is a compelling multiclass option to consider four or five levels in sorcerer or on rogues and rangers. Seeing through magical darkness is yucky good, but mainly when you can use that to get advantage on attacks consistently or impose disadvantage on other attacks because of it. Thus, you’ll want to build accordingly.
Strength of the Grave pairs perfectly with Eyes of the Dark as a flavorful and occasionally life-saving tool to keep you up long enough to drop a Darkness and flee or Misty Step out of there. I don’t typically love features that only trigger on death, but when they’re alongside a powerful utility tool, I’m all for them.
6th Level: Hound of Ill Omen
Summoning magic tends to be outrageously good in D&D; Hound of Ill Omen I think fits in this category. 3 sorcery points for a concentration free summoned Dire Wolf hellbent on killing one specific creature is an interesting direction to go with for a feature.
If that’s all it was, though, it wouldn’t scale that well. Fortunately, the designers thought of that, as it also imposes disadvantage on saves from spells you cast on the target it's mauling with its 2d6+3 Bite that can drop the hit creature prone.
If one isn’t enough for you, you’re free to summon another one round after round. As long as you can keep spending the points, you can keep conjuring shadowy wolves to devour the creature. To make matters worse, they all have Pact Tactics, rewarding you for piling them on.
The major limiting factor then is its cost and competition. Once you have eight or nine points to throw around, using this once per fight or long rest feels reasonable. After that, its probably going to start costing you spell slots.
14th Level: Shadow Walk
Way of Shadow does a lot of fun darkness teleportation stuff. Shadow Walk basically does the same thing, but comes with the bonus of being attached to the class option that comes with empowered magical darkness only you can see through. You can cast Darkness you can see while a different area of darkness to get a guaranteed bonus action 120 ft. teleport to any space you need to go.
Even without that use case, Shadow Walk is a blast to play with. You’re majorly encouraged to keep it dark and adventure at night to keep blinking around from shadow to shadow. It isn’t always going to be online, as sometimes you have to fight in daytime or by brilliant, unquenchable flames. You can still typically make use of it with clever positioning, key eyes for where is just in dim light, and tools to swiftly snuff light sources as you go.
18th Level: Umbral Form
Umbral Form closes out Shadow Magic with a transformation that provides you resistance to all damage and the ability to walk through creatures and objects. You basically become darkness.
The main issue with this is its cost- 6 points is a lot, even at 18th level. I think there will be some moments where you’ll want the resistance, but a lot of the time, you’re going to prefer summoning two Hound of Ill Omens or casting Darkness three times. There will be some tables where you’ll do all of that in a single fight anyway, in which case this is all upside.
Alongside 9th level spells, this is still a great feature to get. Sometimes you just need a bonus action tool to mitigate a truckload of damage. This does that while still giving you space to cast Meteor Swarm.
All Together
My main gripe with Shadow Magic is its lack of stuff to do outside of spending sorcery points, especially prior to 14th level. What it does let you do for those points, though, definitely is a distinct, awesome experience that delivers on the evil dark shadowy sorcerer whose origins are tied to the realm of the dead.
I think a modern printing of Shadow Magic probably would get one free use out of all of its features before asking you to spend points on them, and that option would be nuts. Where this currently stands, you’ll feel a bit strained for resources early, but when you do spend points on some of these features, my lord are they going to have an impact and do exactly what you want them to.