How is the balance on my homebrew Sorcerer Origin (Wild Magic, alternate)?

Question

I've made a homebrew on the "Wild Magic" sorcerer, with less focus on "unpredictable" effects and more focus on "sudden floods of raw magic power". I would appreciate any constructive feedback. Much of the flavor text stayed from the original phb Wild Magic.

Sorcerous Origin

Different sorcerers claim different origins for their innate magic. Although many variations exist, most of these origins fall into two categories: a draconic bloodline and wild magic.

Wild Magic (alternate)

Your innate magic comes from the wild forces of chaos that underlie the order of creation. You might have endured exposure to some form of raw magic, perhaps through a planar portal leading to Limbo, the Elemental Planes, or the mysterious Far Realm. Perhaps you were blessed by a powerful fey creature or marked by a demon. Or your magic could be a fluke of your birth, with no apparent cause or reason. However it came to be, this chaotic magic churns within you, waiting for any outlet.

Wild Magic Surge

Starting when you choose this origin at 1st level, your spellcasting can unleash surges of dangerous untamed magic.

When you cast a sorcerer spell of 1st level or higher, roll an additional d6. You take damage equal to your proficiency bonus unless you spend one sorcery point to prevent it. On a 6, give yourself advantage if you are making a spell attack roll, or disadvantage on the targets' saving throws. If neither of those can apply, double the duration of the spell's effects.

Chaotic Synergy

Starting at 6th level, your innate connection to magic itself allows you to sense its chaos in the air when a spell has been cast. The spell's residue lingers in a 30 foot radius for 1 hour per spell level.

When you are within an area that has this residue, your spell attack rolls can critically hit on both a 19 and 20 and your Spell Save DC is 1 higher than it otherwise would be. This effect can only apply once per turn.

Controlled Chaos

At 14th level, you gain a modicum of control over the surges of your wild magic. Whenever you roll your Wild Magic Surge, you may roll any number of d6 instead of just one. You take damage for each d6 rolled, and may spend one sorcery point to prevent damage from each die separately

When you see another creature within 30 feet of you casting a spell, you may apply your Wild Magic Surge to their spell as a reaction. You still take any relevant damage for this surge.

Spell Bombardment

Beginnning at 18th level, the harmful energy of your spells intensifies. When you roll damage for a spell and roll the highest number possible on any of the dice, choose one of those dice, roll it again and add that roll to the damage. You can use this feature once per turn.

Answer 1

It's problematic

Wild Magic was already the weakest of the sorcerous origins. While ordinarily its problems stem from requiring the GM to tell you to roll at every possible moment just to stay relevant, now the class gives you a one in 6 chance of your spell having advantage at the cost of every spell you cast also draining 2 hp (or more at higher levels). If you were rolling a d3 this would be essentially a less good heighten spell-- you'd spend 3 points and on average one of the three spells you cast would be heightened. Instead you roll a d6. Sure, it can apply to almost any offensive spell instead of just those with saves, but that hardly makes up for the massively increased cost. I would go so far as to say this feature is a penalty more than a bonus-- it adds another cost to your spells that may occasionally prevent you from being able to cast even if you still have spell slots. Normally the 1st level origin feature is a whole pile of different useful abilities. Instead you get one single ability and it makes you worse at spellcasting while adventuring.

The 6th level ability will be always-on whenever you cast a spell. You can either cast a cantrip as an action alongside a quickened spell or just cast after an ally for your first spell, and then your spells will trigger off the previously cast spells from then on. Consequently, you can expect improved spell critical and +1 DC forever. This is pretty good.

At 14th level you get the option to take even more damage. You can now take 5 levels worth of average hp gain in damage to probably replicate a metamagic that costs 3 sorcery points! This is made worse by the fact that it is also broken. While most spells will just be getting advantage, you can also use it to double the duration of certain spells, which can self-stack. So, while the feature is bad if used in the intended way by a sorcerer who's adventuring, a sorcerer willing to kill themselves can take infinite damage and make any eligible spell permanent. Given they are level 14, this is equivalent to a 1000 gp cost on permanency for any spell with no save or attack roll. That breaks the system pretty hard-- the game doesn't expect you to deck you and your party out with every non-concentration buff spell on the sorcerer list (or, at least, as many as you have spells known) as permanent effects regardless of their normal duration. Also summons.

The 18th level ability is a 10-25% increase in damage. You don't cast damaging spells, because those use attack rolls or saves so that is bad for you. Assuming the 14th level ability were fixed, though, this would be a fairly weak capstone, but since it's a capstone balance doesn't matter as much.

Answer 2

The Balance Is Bad

Wild Magic Surge appears to be mandatory, making spell use fatal at low levels.

Chaotic Synergy is really strong. The benefits are enough that might be worth slogging through the uselessness of being unable to use your primary class feature for five levels, without killing yourself.

Controlled Chaos is suicide.

Spell Bombardment seems to fine. Not great, just fine. Certainly not worth the brutal self-mutilation of the rest of the class variant.

Overall, the design seems badly flawed. Sacrificing hit points from one of the least durable classes, just to use the defining class feature, is a punishing trade that discourages players from choosing this class variant. It also favors a "one shot" mentality, since the character is going to get killed by their own class features at some point. It also limits play styles - a Wizard can use magic to function as a tank, but this "self destruction" Sorcerer is going to be lucky to survive functioning as ranged damage even if no foes attack her.

The concept of "sudden floods of raw magic power" is interesting. Difficult to balance; most of the mechanics that could represent that flood (advantage on attacks, disadvantage on saves, higher save DC, additional damage, additional duration) would make the character the most powerful spell caster class. What the presented version models is "self-destroying surges of magic" not floods of raw power.