Resonance stone might need a nerf, 1d8 damage die bonus instead of vulnerable? or add a saving throw DC13 successful save grants entity immunity to the effect for LR? or both?
I don't see a problem with the Resonance Stone itself, I just think doubling 4d8 is a bit much. Remember, Steeped in Bliss also has a substantial downside, it's not just a straight buff.
Alternative maybe change shadow blade damage type to necrotic damage?
Concentration definitely still needs to be a requirement for this spell it too powerful for it to not have it.
For the spell not to have a concentration requirement it need to be reduced significantly in power, no upcasting, and no advantage on dim light targets.
Why is it that no one uses Shadow Blade Ring? Having to maintain concentration for your melee weapon is a BIG ask. Paralyzed? Knocked off your feet? Put to sleep? Slip on ice or grease? A dog farted too hard in your general direction? Congratulations! You've lost your weapon for the rest of the battle at minimum!
Even if SBR had a per turn cooldown, it'd remain just as frustrating because not only would you be targeted because of concentration, you'd also be putting yourself in harm's way by being in melee range, magnifying the difficulty of maintaining concentration. In that situation, you'd just take turns recasting SBR and losing concentration, and occasionally getting in a hit.
The concentration requirement is just too big of an ask. It promises a cycle of frustration with Shadow Blade that the new version gets to bypass completely.
No upcasting? I already said it, so yes I agree with it, for previously stated reasons.
No advantage? Meh, it wouldn't really make noteworthy difference IMO. If attacking from within a cloud, you pretty much always have advantage either. Distinction without a difference.
Necrotic Shadow Blade? Why bother?
