So, I've moaned a bit about certain aspects of 5e, including sorcery. As I've been playing casters recently, and planning others, I've spent a lot of time thinking about spells. I just want to throw out some ideas I've had for spells.
The Elemental Evil handbook offers a lovely fun selection of new spells. Some of them have unexpected potential.
I'm pretty sure mold earth was intended to be a digging tool, but what it gave us is an infallible pit trap. You can instantly move a 5' cube of earth away, and although the spell specifically says the movement doesn't cause damage, it says nothing about being unable to dig around creatures or any defences whatsoever. Dig a 5' cube away under a target and drop them into a hole with no saves or attack rolls. Sure, it's only 5', but that should inconvenience them quite a lot. At the very least this should force a Concentration roll for casters. For extra bonus lulz, have two people take this. The first one digs out a 5' cube under an enemy; the second one shovels that 5' of earth right back on top of them. Let's see you take a standard action now, boyo. See also: quicken spell. Depending how your DM interprets all this, it's quite possibly one of the most powerful things a sorcerer can do.
Thunderclap is a decent cantrip, but also has some utility as a way of communicating up to 100 feet. You can use it as a pre-arranged signal that's not amazingly suspicious. You can even use it for Morse Code if you want, just by altering the frequency of your castings.
Maelstrom is actually a surprisingly cool, unsuspicious way to assassinate someone by just drowning them in their bathtub.
Gust can be used to rescue allies from combat, since they can choose to fail the saving throw and leave combat without taking an attack of opportunity. This trick also works with normal shove attacks, although Open Palm monks are best (shove attack with your bonus flurry attack to push an ally 15' without damage).
A DM may rule otherwise, but the rules for control flame state that you can expand a nonmagical fire 5' per round providing there's "wood or other fuel" there. This means you can place a candle next to a wooden fort or palisade, then engulf the whole thing in flames within a minute or two.
Warding wind is a verbal-only spell that extinguishes nearby torches, which means it's a great tool for those moments when you're tied up in an enemy's lair while a candle slowly burns through the rope holding the guillotine over your head. Or for turning out the lights ready for a ninja vanish.
The new flame arrow looks like it's a fantastic new option for the ranger, perhaps even an alternative to hunter's mark. Except... it's a 3rd-level spell, and requires concentration, and lots of things resist fire, and it affects far fewer targets. The only time this is actually better than hunter's mark - a 1st-level spell - is if you're facing something with resistance to most things and vulnerability to fire, or if you're trying to kill a troll and unaccountably have too few ways to deal fire damage in your party despite it being the most prevalent energy type, as in literally every caster probably has a cantrip that will do more damage than this, what the hell is wrong with you?
A cunning plan
Sith-lightning-fanboy witch bolt is almost an amazing spell, except that being 1st-level that would be OP. What you get instead is... just not quite there. The great thing about witch bolt is that you only need one attack roll, and after than deal 1d12 automatic lightning damage. But there are a few problems.
First up, this is your action. If you're maintaining witch bolt, you're not doing any other damage, control or mitigation. How much better is this spell than simply using a cantrip every round? A fire bolt will do 1d10 on a hit, which is slightly less damage on average, and requires attack rolls each round. A witch bolt does on average 6.5 damage per round if you hit in the first place, to a maximum of 65 damage; a fire bolt will do 5.5 damage on a hit, so roughly 3 damage per round - the numbers will depend on AC. The witch bolt is more of a gamble, but you can always fall back on fire bolt if you do miss in the first round. So far witch bolt is looking pretty good.
The cost here is really opportunity cost, because that precious slot could have been spent on another 1st-level spell that had a better up-front benefit. Shield, say. With fire bolt, you also have concentration available to use another useful spell, like charming the rest of the enemy while you fry this one sorcerer-queen.
The second serious problem is that range. 30' range is bad for a number of reasons. One is that it means you're within easy attack distance, which is rarely where a mage should be. Particularly not a mage who's trying to maintain concentration. The other is that it isn't very difficult for an intelligent enemy to just move away and break your spell automatically. Any Named NPC should certainly do so, and Named NPCs with their typically-high ACs are where this spell is most valuable. Unless you were right up in their face when they cast, an target can probably move back a few feet, move back exactly where they were, and then return to killing you. The main exception is targets engaged in melée with your allies, or stuck in a pit or something.
Third, there's that concentration. This isn't even like normal concentration; it's a whole new level of impracticality. Your witch bolt fizzles as soon as you take any other normal action! So no maintaining concentration and casting a different spell, or even Disengaging from that mob of orks who jumped you because you're within 30' of the enemy like a fool. As soon as something goes wrong, this spell dies, which means it wasn't such a great investment after all - pretty much the whole benefit of it is those automatic hits, so it gets more valuable every round. The earlier it ends, the more you wonder whether casting another spell would have been better. If you were just casting fire bolt every round, you wouldn't have that problem. Not only would you be further away, you could switch effortlessly between cantrip-slinging and whatever other action seemed useful.
I'm sure it made sense to someone, but you'd almost think the designers didn't want you to use this spell. Creating a unique subset of concentration just to make it more difficult to use looks a teensy bit pointed. There doesn't seem any good reason for this. You don't have to spend an action to maintain any other concentration spell. Call lightning is incredibly similar to this spell, but you have complete freedom of choice over whether to zap people or not. Even logically it doesn't seem fair; you could easily argue that on turns when you don't invoke witch bolt, the current is simply too weak to hurt anyone, and you channel extra energy through it on turns when you zap.
So this spell relies heavily on keeping focused on a target for round after round, but it's actually very difficult to do so. If circumstances are ideal - say, your target is stuck in a hole or behind bars - you might ask yourself, why not just spend a little longer and do this with a cantrip? Bear in mind that if you do flub that first attack roll, the whole thing goes to waste.
Lots of people On The Internet are scoffing and scorning witch bolt for pretty much these exact reasons, only usually with more invective.
Let's make witch bolt awesome. Here's the key: stop thinking of this as a general spell. This is a very specific spell. This spell is the gods' gift to the blue and bronze draconic sorcerers.
Lightning is a very poor choice most of the time, with only a couple of lightning spells to benefit from when your bonus damage kicks in, but this here ranged 1st-level lightning spell? This lightning spell with ongoing damage? Golden.
So, you're a 7th-level sorcerer, say, and some scary enemies appear. Here's what you do: you approach and cast true strike, that under-appreciated cantrip. Next round, you target the biggest mofo in sight and cast witch bolt as a Distant Spell for a measy 1 magic point with advantage on the attack roll. Assuming you didn't mess that up, you spend the rest of the combat dealing an automatic 1d12+Cha lightning damage to your target every round. You probably only deal 1d12+3, because at 4th level you took Spell Sniper, which means the range on that spell is 120', making it almost impossible for enemies to escape, even though you now immediately take the opportunity to withdraw well out of attack range.
If your enemies are a bit slower, of course, or perhaps bogged down in melee, or maybe a kindly druid has entangled them for you, then you instead use Twinned Spell for another measly 1 magic point, and hit two targets at once, and continue dealing both of them 1d12+Cha lightning damage every round until they die. You can, if concerned, burn a second sorcery point to extend your true strike to 60' and minimise the risk of getting attacked. Or twin it insted, and make sure you hit both those targets of the twinned witch bolt. That does mean hurling sorcery points around, but spending them one by one like this gets some of the biggest bang for your buck.
"But witch bolt doesn't do enough up-front damage!" I hear you cry. Well, you can drop it in your highest-level slot to boost the initial hit, if you want, because Distant Spell cares not what it boosts, it's always 1 sorcery point. More likely, though, you simply dump some fireballs (still, sadly, just much better than lightning bolt most of the time) first before switching to sustained damage.
Once you hit 14th level, of course, you'll have fewer concerns about being attacked, because you'll be flying 50' above the battlefield (out of range of many spells) raining Twinned electrocuty death down on your enemies and cackling madly.
I thank you.