Is this "Rebound Energy" Arcane Tradition homebrew feature balanced?

Question

I am currently working on a homebrew Arcane Tradition for Wizard, based around the concept of modifying spells, amplifying or mixing them by directly tampering with the Weave, at the risk of attracting... unwanted attention.

While I am still trying different things for the later features, I would like to make sure that the first feature of the tradition does not break anything. If worst comes to worst, I can rework it and swap it out with another later feature.

Here is the feature as of now :

Rebound Energy: Starting at 2nd level, you have learned to channel the pure magical energy shared by all your spells, and redirect it to augment another spell. When you cast a spell of 1st level or higher, you may choose to expand additional spell slots of any level. When you do so, the spell you cast is considered as being cast one level higher for each additional spell slot level used. For example, when casting a 3rd level spell, expanding an additional 2nd level spell slot, or two 1st level spell slots, allows you to cast your original spell as a 5th level spell. A spell's level can only be increased by up to your proficiency bonus. You cannot use this ability for spells cast through a magic item or scroll.

The intent with this ability is to grant the player the option to give their spells more power, at the cost of using one or multiple additional spell slots. However, I thought giving players the ability to upcast spells at 8th or 9th level early on, even while needing all their resources, could possibly break balance, so I limited the maximum possible augmentation to proficiency bonus (i.e. +2 early).

This limitation is also meant to prevent players from upcasting spells too far past 9th level, if the DM allows it. After all, in this case, a 20th level wizard could use all their spell slots to cast a 89th level spell. This is a lot of resources invested in a single spell, but at that point I think it's fair to assume that there's no way this is balanced ("No, you are not casting a 94d6 Fireball. Yes, even if it costs you all your spell slots.").

In its current state, how does this feature compare with other Arcane Traditions?

Answer 1

The D&D spell system was not designed for this.

For most spells, sacrificing a spell slot for an upcast is pretty unexciting. But, for a small number of spells, it's amazing and overpowered.

One example is hold person, which gains additional targets per spell level. So normally a wizard could burn a second-level slot to hold one person, but with your new variant a wizard could burn two second-level slots to hold three people at once.

The invisibility spell has the same scaling.

Upscaling raw-damage spells such as fireball is likely to be unexciting -- spending a whole spell slot for +1d6 damage usually won't be good.

But the conjure spell line gives great returns for upscaling. For example the fourth-level spell conjure minor elementals gives twice as many creatures if you use a sixth-level slot.

Some summon spells, such as summon construct, also scale very well with spell level.

Ultimately if you try to do this you're going to have to go over every spell in the list and selectively nerf or veto the ones that have become broken.

---

I also would add: there's an existing problem with D&D, where spellcasters can burn all their spells in one fight, and be amazing and overpowered, and then refuse to adventure any more until the next day. We refer to this as "going nova". The game isn't balanced for this -- DMs are supposed to enforce something like six encounters per day -- but many DMs don't want to run that much combat, or don't have a way to prevent the group from resting.

Your proposed modification makes this problem worse, because spellcasters will be able to burn two or three spell slots per round, instead of maximum one.

Answer 2

It breaks everything

Generally, upcasting spells is a poor investment.

However, as a third level Wizard, I can bump one spell to 6th level if I have 18 intelligence? Yes, please. Nova damage is the best damage. I’ll take down your BBEG in one shot and use cantrips for the rest of the day any day of the week and twice on Sundays.

Answer 3

If you were to make this balanced it would make no sense at low level

The feature is absolutely unbalanced. Just like for example a feature that would increase proficiency bonus this disables basic balance factors that should not be tampered with.

This could be balanced if the maximum spell slot level accessible was the same that the caster has anyway. I.e.they get more of their best level spell slot. This would still be powerful but not tamper with core balance tools like your feature. However, doing it like this makes no sense as second level feature because the wizard does not have access to higher level slots at this point.

Your flavor is on point though for a feature that messes with things best left alone.

Besides making only spell levels available that the character has anyway, there probably should be some cost associated with upgrading spell slots. You can look at the Flexible Casting feature of the Sorcerer as a starting point.

Answer 4

As others have pointed out, this feature is completely broken. But even if it weren't, I as a DM still wouldn't allow it.

You said that this ability works by manipulating the Weave. That implies that you are using Forgotten realms as your setting. In that setting spells above 9th level are not allowed (anymore). Mystra, goddess of magic and architect/guardian/custodian of the Weave herself banned them after the little incident that destroyed the greatest(self proclaimed!) human empire in the history of the setting and killed the previous goddess of magic.