I actually took a crack at this spell a while back
Flame Blade Spell 2
Fire, Conjuration
Traditions primal
Cast (aa) (somatic, verbal)
Range self; Targets self
Duration sustained 1 minute
You conjure a weapon made of flames into your hand. Whenever you Sustain the Spell you may make a strike with the weapon as a melee spell attack with a +1 item bonus. On a success you deal fire damage equal to 2d6 plus your casting modifier. On a critical success you additionally inflict 1d8 persistent fire damage.
Special: you may sustain this spell multiple times per turn to make additional strikes.
Heightened (5th) Your Strikes with the weapon have a +2 item bonus to attack and deal fire damage equal to 4D6 plus your casting mod on a success, and 2D8 persistent fire damage on a critical success.
Heightened (8th) Your Strikes with the weapon have a +3 item bonus to attack and deal fire damage equal to 6D6 plus your casting mod on a success, and 3D8 persistent fire damage on a critical success.
Here is another shot at conversion for my party druid who wanted a melee option.
Flame Blade — Spell 2
Conjuration
Traditions Primal
Cast Two actions - Somatic, Verbal
Duration 1 minuteA 3-foot-long, blazing beam of red-hot fire springs forth from your hand. You wield this blade-like beam as if it were a scimitar. Strikes with the flame blade are melee spell attacks. The blade deals 2d6 plus your spellcasting ability modifier Fire damage (Forceful, Sweep). A flame blade can ignite combustible materials such as parchment, straw, dry sticks, and cloth.
Heightened (5th) The blade's damage increases by 1d6 Plus 1d10 persistent damage on a critical hit.
Heightened (8th) The blade's damage increases by 1d6, the persistent damage increases by 1d10 and Fire damage dealt by this weapon (including the persistent fire damage) ignores the target’s fire resistance.
Hmm... that is basically giving them the spell Magic Weapon, which primal doesn't have access to. It also doesn't require the starting weapon and does fire damage instead of slashing. In many cases the fire damage may be advantageous over flashing, but it also would be less effective against things that resist fire, which isn't insignificant as a weakness until your eighth level version of the spell.
It also offers some strong heightened versions that aren't available with Magic Weapon. I was going to say that it offered Greater Striking at a level where they generally haven't found the rune yet, but looking at it, it is more like they get the Flaming property at 5th level heighten, and Greater Flaming as well as Greater Striking at 8th level. This means it is more powerful than magic weapon since it heightened, but isn't wholly unbelievable from a potential balance standpoint.
For comparisons Flaming Sphere does 2d6 + Spell level d6 fire damage, and Spiritual Weapon's 1d8/spell level/2 + spellcasting mod.
2nd | 4d6 flame | 1d8 + spellcasting | 2d6 + spellcasting
4th | 6d6 flame | 2d8 + spellcasting |
5th | 7d6 flame | ____________________ | 3d6 + spellcasting + persistent on crit
6th | 8d6 flame | 3d8 + spellcasting |
8th | 10d6 flame | 4d8 + spellcasting | 4d6 + spellcasting + persistent on crit + resistance bypass
At second level, it does more damage on average, but does only has flame damage when compared to spiritual weapon's force or normal weapon type damage options. It however offers the ability to use it multiple times in a round with out sustain if I understand correctly. The probability would be it would do less damage than a flaming sphere. But it doesn't require sustaining if I understand your proposed mechanics. It also has the ability to use it for multiple attacks, allowing you to potentially multiply the amount of damage by number of attacks made, but with map it should lower efficiency each time.
At fifth level, It again beats the damage done by spiritual weapon (by a couple again), but again is limited to flame damage. it gets bonus damage on Critical however that Spiritual Weapon doesn't. (oh Spiritual weapon can be used at range, that might be a factor too however) Compared to Flaming Sphere, it will generally in one action do a bit less than double what your new spell would. The potential is to do a little more with two actions, both hitting, or significantly more with three actions managing to hit.
At eighth level a flaming sphere would do potentially remains doing about twice the damage for one action, it might look like more than that, but by that level the spellcasting modifier is likely significant. As far as spiritual weapon, yours does slightly less damage due to smaller dice, but the persistent likely makes up for that over the long haul. The Bypass resistance reduces the limitation of bein limited to only flame damage since you can now bypass resistance. The fact you can use the weapon multiple times a round here is key.
I worried yours seems to do consistently more damage than spiritual weapon does, however as it can only do fire damage, and does not do range. The difference is likely not that different than say half an attribute modifier, which is probably ok for the 2nd level version. The d10 persistent damage and getting rid of the fire resistance are pretty significant boosts at that level.
I'd contemplate switching it from duration 1 minute to duration sustained 1 minute. And offer that the spell gets allows one free strike if they spend a 1-action doing the sustain. Subsequent actions that round they can use the weapon to make other melee strikes as it is a weapon, but allowing use of the spellcasting modifier for the to hit and damage modifiers. (but does not accept/adopt other magical effects by runes that might try to affect it) So no using doubling rings or other magics to try to put other property or fundamental runes on it. That would take away another advantage of that spell over Spiritual Weapon, in that it is fire and forget, while Spiritual Weapon requires sustaining.
You might be able to give the 2nd level a +1 item bonus to hit (+2 at 5th, +3 at 8th) and still be in realm of possible.
You might also be able to make its base level be Level 1, strikes use spellcasting modifier to hit, and have it do 1d6 fire damage (without spellcasting modifier to damage I think at level 1) The 2nd level version would then be a heightened version that gives extra die and spellcasting modifier. Granted, it complicates the progression a small bit, but it might still be useful as a 1st level spell.
@Kekkres: Your damage levels and persistent damage levels seem too overboard from my perspective since they can try and make 3 strikes each round (so potentially some 28 potential strikes per spell slot). Individual hits with the weapon shouldn't be getting close to the 1/round damage potential of the other spells limited to one use per round. You were right that you could likely justify adding item bonuses to hit on it as a temporary 'enchanted' weapon. Obviously, your game do what seems right for you, but I'd be concerned about it being to readily exploited, but maybe I'm missing something.
And all because the GM couldn't spell Shillelagh :-)
Jokes aside I like the idea of the spell but I am not keen on the theme. Druids with metal swords of flame? If you wanted a level 2 spell I'd prefer to heighten Shillelagh or make a variant of it.
Well first, I think it is important to recognize the curved arc of flame, could be mistaken for, and patterned after a metal scimitar, but I believe the intend was that is was conjuring a jet of fire, not a metallic curved blade emitting fire.
I have to admit that I am surprised I didn't look up Shillelagh when I was comparing spells. But it, like magic weapon doesn't have heightened versions, and so really is just a more limited version of Magic Weapon, more limited on what type of weapon it could target, but also providing a boost against certain specific types of enemies.