I never paid attention to those guidelines, and chances are you'd be OK ignoring them as well. If the party is just exploring a ruin with nothing pressing them for time, there's no reason they shouldn't be as safe as possible, and trying to artificially boost encounter numbers is silly.
On the...
Use the fog cloud to divide your enemies while your group concentrates on one half of them. If the other half wastes a few rounds moving to an improved position, it's worth it.
Hatnap: Enlarges a hat to enormous size so that the party can rest safely within its confines.
Chard Monster: Conjures an enormous leafy green shambling mound that is rich in vitamin A, K, and C.
Yawn: Immediately ends your concentration, and then next round interrupts the target's...
Thread necro but hey it's an evergreen topic.
I usually let druids find/make some wyvern or hydra scale armor that's equivalent to half plate by level 5-7. Bonus if they can find a suitable creature and save on materials.
Still call it bloodied. In fact we still usually use the terms "standard actions," "minor actions," and "healing surges" even though I think by now we've been playing 5th longer than 4th now. Several of the players still think standing up provokes OA and you can't use reactions on your turn...
Permanently crossed eyes, and general clumsiness, giving disadvantage on Perception checks and Dex checks.
Edit: Didn't read the OP, oops.
Player re-rolls secret initiative each round, but doesn't know when they go until their turn comes up.
Independent of this thread I was thinking about just making stones take up one attunement slot regardless of the number you have. They aren't exactly common IMC.
It seems to me the flaws system is meant to encourage and reward roleplaying for beginners, rather than be a straitjacket for the DM to exploit.
PCs aren't required to follow their flaws blindly, but they are a strong indicator of how the player decided their character should act.
I wonder what % of this data was drawn from D&D Beyond, where feats are largely inaccessible to free accounts. That would also skew the numbers toward the basic races of human, elf, dwarf.
I was under the impression it didn't dispel or counter the original casting. It just lets you learn/prepare up to 3 additional spells if you meet the conditions. Nor does it give you free slots to cast them.
Maybe a little strong for an uncommon but seems fine. Definitely stronger for classes...