Sounds good until the goblins start at a position to surround the enemy. Or just surprises the party, like goblins are made to do. Wizards can be good with AoE's. Not very good at taking them or resisting most effects in general. Even a 20th level wizard's greatest defense against a wisdom save is their +11 proficiency (if they went +5 wisdom which doesn't seem likely). And they're looking at saves in the upwards of DC 22-23.
And without magic items the fighter has a 21 AC at best versus a +18 to hit, and their highest save is a also a +11, only their's is Con, which is going to half damage anyways most of the time.
Also, the ambushed wizard activates contingency to dimension door away, then begins destroying the goblins from a better positon. Or casts Fire Storm. Or does a Wall of Force/Stone/Fire.
Meanwhile... the fighter now has multiple turns, because they now need to reach each goblins. So, they are still in a worse position to deal with them all quickly.
There's no losing if your character isn't dead. Let them do whatever their goal is, kill them when you get out and clean up the mess.
It's some weird fixation on this imaginary narrative where you must do something the right way or else you've "failed."
This isn't a videogame. You can just do stuff the way your character would do them. Imagine a scenario where a level 20 team consisting of a Ranger, warlock, Rogue and Paladin must get to the Plane of Fire to prevent an Archdevil from their whatsamacallit. They never prepared plane shift nor wish. Now what? The game ends because they built their characters wrong?
Magic could solve this issue, but they don't have the magic to do so. Now what? They give up? No more campaign?
No, they persevere despite their builds and continue the game. Maybe they never do so and must wait until after the archdevil has completed his plan. They didn't fail because there's no fail state, they just deal with what's after.
Yeah, if you fail to prevent the enemy from achieving their goals. You've lost. the Archdevil merged the planes, now the Devils have free reign enter the material world, and you have no way of reaching them to end the ritual. You are fighting a losing war of attrition in a world no overrun with Devils.
Sure, you aren't dead yet, but you will be, and you can't stop them. I guess the campaign can continue in this new ruined world, but most people would roll up new characters. Probably some magic-users so they stand a chance of stopping whatever goes wrong in this new world.
Or, more than likely, the DM gives you a friendly mage to solve that problem, so the plot isn't "and the heroes had no way of stopping the apocalypse, so the world ended in fire and death."
Until combat starts, where a caster is a useless bag of meat in their worst case scenario and the only worst-case scenario for the fighter is not having at least 1hp.
Cantrips are a thing. And quite useful. Also, by 20th level, you have some 1st and 2nd spells at will, so that is a thing too.
Not exactly what I'd call a "useless bag of meat"
How's a high-level caster going to survive a single encounter against one of D&D's most iconic enemy, the Beholder?
Quite well. Most casters I've seen in beholder fights are smart enough to move in and out of the anti-magic zone. They move out, hit the beholder, then move back in so the Beholder can't hit them with their eye rays.
And, since the Beholder only gets to change it's cone at the start of its turn, if it moves the cone to hit the wizard, they have full access to all of their magic
Amusingly, it is generally barbarians and melee fighters who have the hardest time, since the Beholder is usually flying out of reach, and anti-magic prevents them from safely flying up to stab it.
Casters suck against saving throws, too. Force a save on them, any save, and their only means of defense is either having casted a spell prior to getting hit or their having proficiency in that save. The more common saves being least likely to have high ability scores with exception to the cleric and druid.
They are literally no worse at saving throws than anyone else. And since they tend to have proficiency in mental saves, they tend to be better off than fighters and barbarians against some of the worst effects.
So instead, as Frog said, let the wizard be a wizard, and give the fighter meaningful option that makes its varying roles fun to play, instead of bringing the figther to do the things of a wizard. In the end, if the player really wanted a PC that can have the whole versatile array of a spellcaster, they would play a spellcaster, not a fighter.
In short, the breadth of options for the fighter should add to the general idea of a fighter, not make them another class entirely.
How would you do that? I dont know, myself.
I think the only way to really do that is the "fighter's only go to level 10, then they get a more impressive prestige class" route. Because I think most of us agree that the idea of having the classes inherently unbalanced where the wizard is a superior choice in 80% of all circumstances is a problem.
Perhaps flip the problem around. Let's say we have a party of 4 spellcasters. The BBEG is a high level fighter. What could we do to make her terrifying to the party?
I think the biggest necessity would be very high magic resistance. The BBEG would need to be able to shrug off or fight through most non-damage spells, and take minimal damage from damage spells.
Also the BBEG needs some way of stopping spellcasting. Like if she gets in melee combat with the spellcaster, the spellcaster simply shouldn't be able to get a spell off.
Yeah, the first and biggest thing would be to make the BBEG practically immune to magic and able to ignore its effects.
I mean, a simple combo like Heat Metal (5th level), Cloudkill, and Wall of Force (using only three casters of our four casters) can deal 550d8 damage. Even with saving for half, I think that is about 300d8 damage, which is over a thousand damage from succeeding the saves.
Without the ability to ignore magic, the BBEG dies.
