Because a low-level spell cast in a high-level slot is nowhere near as good as a "native" spell of that level. Compare shatter to fireball. Shatter cast in a 3rd-level slot deals 4d8 (average 18) thunder damage in a 10-foot radius. Fireball deals 8d6 (average 28) fire damage in a 20-foot radius. That's over a 50% damage boost and four times the area.Good day all,
I understand that by the rules, PHB pg 164 that Extra Attack from multiple sources do Not stack. I think we can agree that's reasonable. What I've been thinking about is:
If Multiclass Spellcasters (PHB pg 164-165) get level stacking (more spell slots and higher level slots), why couldn't (or would it be 'OP') martial classes get something similar? For example: 3rd level Fighter / 2nd level Paladin = 5th level martial character ... therefore Extra Attack. Sure you'd need to make some adjustments for something like Valor Bard (6th) or such, but I'm curious why the concept of stacking martial levels didn't make it into the rules.
To get the powerhouse spells, you need actual 3rd-level spells, not just 3rd-level slots; which means you have to reach 5th level in a single caster class, just like the martials need 5th level to get Extra Attack.