Drove a tank off a cliff. Unfortunately, the game also decided to put a checkpoint after going off the edge. Cue death happing over, and over, and over, and over, and over, and over.
Climbed a tower that only let me use magic. At least two types of enemies have a permanent Reflect spell, that cannot be Dispelled, one of whom has a crapton of hitpoints, no weakness, immune Death, Gravity, and that spell that banishes, and casts endgame-level spells. Most of the rest cast powerful attack spells, and often counterattack with Silence spells.
I get to the top of the tower, going through a good stock of MP recovery items, and find an accessory that allows casting two spells at once. Huzzah. Try to leave, and fight the boss. This boss is immune to everything but one elemental damage type(to which he is weak), but he changes his weakness every time he is hit with a spell, including Libra(which informs you if his current weakness, but then changes it. Quantum mechanics, eh?), and some of the elements he can become weak to are impossible to actually cast on him.
After savescumming like hell(using Libra to get his weakness, then reverting and using a spell that hurts him), I finally kill him. Turns out, on death he casts a spell that hits my entire party for more than twice their maximum hitpoints, killing them all without any way to stop it.
Final Fantasy VI, the Kefka fanatics' tower. So fucking glad I made a savestate to before entering the tower.
Note, that enemy with perma-Reflect, deadly spells, etc., some kind of witch-girl thing. I took out two of them during my acsent. Had to kill them by casting Reflect on Celes, and then repeatedly hitting her with Fire(the cheapest attack spell I had) to bounce it back onto the enemy, doing about 250 per turn on an enemy with 9000. Thankfully, they're vulnerable to Stop.