Help with a spell design: Minor Lycanthropy

[Arkhios]

I'm not well versed in spell design, so I came here to ask help.

I have this idea for future use, which could grant a character limited lycanthropy through the means of magic. This lycanthropy wouldn't change the character's alignment, but would confer abilities such as multiattack and natural attacks as for a full lycanthrope for as long as the spell lasts.

Only limitation would be that the spell should be available to all spellcasting classes, but not something you can get instantly when you learn spellcasting. Somewhere between 2nd and 4th level. Although learning it might require some special effort.
I believe the spell school would be Transmutation, though I suppose it could be Enchantment as well, considering that real Lycanthropy is a curse.
Better yet if said spell could be made into a potion.

[Ninja_Prawn]

*Ninja_Prawn's Obligatory Post*

Base it off Polymorph, but make it either more limited or add in enough drawbacks to drag it down to spell level 3. The MM werebeasts are CRs 2 to 5, and Polymorph can turn you into a monster whose CR = your level. Spell level 3 is ECL 5, so that works out perfectly.

I'd call it transmutation, for sure.

[Arkhios]

*Ninja_Prawn's Obligatory Post*

Base it off Polymorph, but make it either more limited or add in enough drawbacks to drag it down to spell level 3. The MM werebeasts are CRs 2 to 5, and Polymorph can turn you into a monster whose CR = your level. Spell level 3 is ECL 5, so that works out perfectly.

I'd call it transmutation, for sure.

Good idea, I hadn't thought about Polymorph at all. Maybe I could add some level of recklessness to the spell, like Reckless Attack from barbarian, for the duration. or something?

[Ninja_Prawn]

Good idea, I hadn't thought about Polymorph at all.

I guess that sort of thing is why everyone thinks I am some kind of spell-brewing genius...

Maybe I could add some level of recklessness to the spell, like Reckless Attack from barbarian, for the duration. or something?

Possibly. You've got to make sure it's balanced; probably base the lycanthrope's damage output on the MM werewolf (13 @ +4)... or maybe go a bit higher, if you're not granting so many defensive buffs. I don't know, it's tricky because there's so many 'moving parts'.

What do we expect from a 3rd-level spell slot? 16d6 damage (standard assumption: a Fireball hits two targets) or a serious impact on the course of an encounter, right? Yeah, you can probably give it more damage.

My starting point (complete finger-in-the-wind time now) is the spell sets your strength to 15 and gives you 3x multiattack, each hit does 2d4+2 damage. Plus maybe some other assorted benefits, like frenzy or pack tactics.

[Arkhios]

I guess that sort of thing is why everyone thinks I am some kind of spell-brewing genius...

Possibly. You've got to make sure it's balanced; probably base the lycanthrope's damage output on the MM werewolf (13 @ +4)... or maybe go a bit higher, if you're not granting so many defensive buffs. I don't know, it's tricky because there's so many 'moving parts'.

What do we expect from a 3rd-level spell slot? 16d6 damage (standard assumption: a Fireball hits two targets) or a serious impact on the course of an encounter, right? Yeah, you can probably give it more damage.

My starting point (complete finger-in-the-wind time now) is the spell sets your strength to 15 and gives you 3x multiattack, each hit does 2d4+2 damage. Plus maybe some other assorted benefits, like frenzy or pack tactics.

I'm rather reluctant to give any defensive buffs with Minor Lycanthropy (dubbed so, as for now), only a minor superficial transformation, giving the precipient bite and claw attacks, like the werebeasts. I think 1d8 for bite and 2d4 for claw (as with werewolf, which is at CR 3, roughly the average of the CR range). Maybe give Multiattack (one attack with bite and claw each) as an action (specifically not Attack action, because an Eldritch Knight with Extra Attacks would be crazy with that kind of boost!), but for as long as the spell lasts, attacks against you would have advantage. And yes, sets strength to 15 (unless already higher). If that's too much of a hindrance, then maybe give minus 3 against non-silvered and non-magical bludgeoning, piercing, and slashing damage. Not resistance, nor immunity, only 3 points less damage from those sources. How's that sound?

Edit: Plus, possibly Keen Hearing and Smell (advantage on Wisdom (perception) checks that rely on hearing or smell).

As to how long should the effect last, I'm kind of between either up to 10 minutes, concentrating, or 10 minutes which you can't voluntarily end. Also, might prevent you from casting any other spells, as if you were raging.