@DND_Reborn I haven't read the entire thread, but you asked for examples of casters punching well above their weight class, which I'm happy to provide. Admittedly, I tend to play more bards, druids, and clerics (I've usually been the guy in my group who'll volunteer to play a healer if no one else wants to). But I have played a few wizards in my time. I will include some non-wizard caster examples, since obviously I have more of those.
There was the time in a 3.x game when an extremely powerful monster ally of ours became infected by an alien parasite. We didn't want to leave her in that state, so my caster cast fly and improved invisibility. In that effectively untouchable state, I proceeded to spam SoD spells until she finally rolled low and died.
In another 3.x game, my buddy made a point of learning every spell he could for his wizard, and scribed one scroll of each spell (because it was so cheap). As such, he often had extremely narrow and clutch spell solutions, like the time we faced off against a dangerous group of fiends and he pulled out some spell that may as well have been named Annihilate Fiend. Cause that's exactly what happened.
There was the time in the very first 5e campaign I played in when we were attacked by giants. My wizard kited one of the giants around with misty step and shield, until one of our fighters was one hit from going down. Whereupon I polymorphed him into a giant ape, effectively restoring significantly more hp than a cleric of my level while simultaneously granting him a sizable combat buff. After that, we cleaned up the fight with ease. I probably could have made that fight much easier, but in that campaign I was really trying not to overshadow the rest of the party.
Earlier in that same campaign, we were being attacked by waves of giant wasps and none of the other party members had AoE. That wizard was an evoker, so I easily fireballed each wave of wasps. I think it was something like 36 wasps, which could have otherwise been an easy TPK for a 6ish level party.
There was also a the time my 5e druid was able to use move earth to activate a titan supercomputer (composed of giant stone monoliths that could be raised/lowered). That one completely altered the ending of the campaign so much that it affected the entire game world and future campaigns (in a very positive way).
There was also a the time that one of my wizard players almost TPK'd the entire rest of the party. The tried to fight back, but ultimately had to use wishes (ring of wishes) and a staff of sanctuary just to escape. And that was despite that I was peeved with him for attacking the party and my rulings we're biased in the party's favor. The wizard had the element of surprise, but the party consisted of 4-5 other members.
That same wizard pulled out True Sight earlier in that campaign, and discovered a powerful campaign secret (True Sight was the only way to find it aside from looking in the right spot while gazing into a mirror, so I never expected anyone to actually find that one).
And, of course, the old classics of using summoned creatures to trigger traps or telekinesis to safely retrieve items or pull levers (etc). I can't recall a specific story about those, but we've used those tricks plenty of times.
