Another Attempt at Multiclassing Balance Adjustments

[Necromas]

What exactly are you trying to prevent here in tiers 3-4? I'm struggling to think of a multiclass combo that would be more powerful than just a straight-class caster at high levels. Maybe some of the one-level-dip stuff like hexblade/paladin, but those combos should be pretty easy to call BS on as DM.

This is way too clunky compared to the normal rules, and I'm not sure any of this is needed. You don't need to be so afraid of multiclassing. There are always trade-offs when you multiclass, and those characters aren't significantly more powerful than straight classes. Usually they can do something really well such as smites or quickened eldritch blasts, but there are costs associated with multiclassing that in play are usually more pronounced than they seem on here, especially being behind in spell level for casters. I'd just allow multiclassing and enjoy the ride.

I agree with these guys, I don't think you should be that worried about allowing multiclassing. Just make sure the players tell you ahead of time what their long term plan is for their build if they're multiclassing and you can just shut it down on an individual basis if their answer is something like "I want to be a Helf Sorcadin that can crit fish with elven accuracy, attack twice, quicken booming blade for a third hit, and smite with all of my high level spell slots" then just talk to them about nerfing that specific build or having them go down a different path.

I do find the rules you proposed interesting though, I think it might be great for a short campaign or a one shot to expand the rules even more and try and have everyone at the table playing with some cool multiclass builds that you couldn't make in the normal ruleset.