Ooh, invisibility. Now I'm somewhere within 100 ft of you, in the air, invisible. Shoot me now!
I think one of the sacred cows that needs to be killed, TBH, is that magic can do anything, AND DO IT IN 6 SECONDS. Some things just need to be off limits without minutes, hours, days, or weeks of prep time.
On Gitpg a few years ago someone had a great post on this (3.5 rules used) It went like this (although I may be messing up a bit)
It made up a hypothaticle adventureing group of 1 10th level fighter with leadership, and 6 18's for stats, his cohort was a 7th level Fighter/Ranger/Rouge, and a bunch of 1st, 2nd, and 3rd level warriors as followers, and a 10th level wizard made with point buy and a 16 Int.
The fighter had a +5 keen shocking weapon, +3 armor, and belt of giant str +4 plus the normal magic items for a 10th level character. His cohort had a +3 long bow and two +3 scimitars plus items of his level. every follower had +1 swords, +1 armor, and 2 potions of cure light.
The wizard was only allowed 1 wand of 3rd level or lower, and scrolls he himself could pen, and no more the 4 of them, and 2 potions of cure light.
two armies are approching the town the PCs are in, from the east agroup of orc, 100 MM orcs lead by a level 5 barbarian Orc, and a level 5 Adept orc. from the west comes 100 book stat hobgoblins, with 50 goblins, lead by a 6th level fighter hobgoblin, and 10 bugbears.
The wizard heads west, the fighter and group head east, this should be easy, the fighter should have a massive advantage, but he does not. You see the wizard uses overland flight, protection from normal missles, stone skin, and mage armor before leaveing the town, then Invisability when close to the enemy. He then summons a few creatures well flying invisable, to fight the bugbears, then starts raining fireballs from his wand on the hobgodlins and goblins(from outside of bow range)
when the wizard wins he can double back to help the fighter and crew.
Replace the wizard with a 10th level druid and it gets worse.