Houserule: supporting spells

[Morty]

So your main point is to prevent casters from having tactics or combat options?

... well, that sure seems... like a great idea.

My main point is to weaken the casters. And they will have tactical and combat options as long as they have spells. That houserule is meant to prevent them from becoming untouchable. And I don't know if it's good houserule. That's why I post it here. To know if it's good or bad and why
But you may be right, I think that maximum spell support level may be too low and restrict casters too much... maybe I'd make it max level spellcaster can cast + INT/WIS/CHA bonus.

DnD is not balanced around 1v1 combat.

But there are 1v1 combats. And if there are 1v1 combats, they should be balanced.

Yes, but the game is overall more fun if wizard hastes the fighter before save-or-killing enemies as then both have more fun.

Also, this limits spells like haste, greater magic weapon, teleport prevention spells, protection from elements..

I mentioned that buffs cast on other people/objects will either count as half of their level or won't count at all.