The spell "Flame Blade" makes a fire sword that you can perform a melee spell attack with. As a druid with higher Wisdom, I would rather have it be based on that than my Strength, but I'm not sure if I would use my Wisdom or Strength, considering it is a 'melee spell attack.
Would I use my Wisdom for the melee spell attack from Flame Blade, or my Strength? Cause I feel like if it's based on Strength, there's no real need for the spell for a druid.
The pertinent part of the flame blade spell description says:
You can use your action to make a melee spell attack with the fiery blade. On a hit, the target takes 3d6 fire damage.
Melee spell attacks are also covered in PHB pg. 206, in the "Attack Rolls" section of the Spellcasting chapter (emphasis mine):
Some spells require the caster to make an attack roll to determine whether the spell effect hits the intended target. Your attack bonus with a spell attack equals your spellcasting ability modifier + your proficiency bonus.
The Player’s Handbook says about spell attacks:
Some spells require the caster to make an attack roll to determine whether the spell effect hits the intended target. Your attack bonus with a spell attack equals your spellcasting ability modifier + your proficiency bonus.
So in the case of Flame Blade, you would use your spellcasting ability modifier + your proficiency bonus.
There are spells that use a melee attack that are not “melee spell attacks”. For instance, Booming Blade and Green-Flame Blade (SCAG, p. 142-143) are not dependent on a melee spell attack. Instead you must make an attack with a melee weapon. They say:
As part of the action used to cast this spell, you must make a melee attack with a weapon against one creature within the spell’s range, otherwise the spell fails.
This would be different than the spell in question because, you are making an attack with a melee weapon, so you would add your modifier that applies to that weapon (Strength or Dexterity) and your proficiency (if you are proficient with that weapon).
