Just fixed
Blood-Chin Fanatic. I couldn't figure out before how it was supposed to be getting the creature's base power rather than its current power. The answer is: it wasn't. It was getting its toughness. Whenever you saw the bug, the creature's base power was probably equal to its current toughness, and so when you gained life equal to its toughness, you thought it was the base power being processed. That's my best guess, at least. Either way, it was erroneously set to toughness instead of power, and I've just fixed that.
Nahiri, the Lithomancer was noted as bugged awhile back. She didn't offer to attach an equipment to the created token. Fixed.
Oath of Druids was bugged as well. It chose a seemingly random creature rather than the first one, and milled more cards than it should have. I've reworked the loop so it is much simpler and doesn't perplexingly ignore multiple creatures.
The Great Aurora - fallenangle and RiiakShiNal got this one fixed and I've tested it. It's working perfectly now.
Den Protector - A mixup between TriggerObject() and EffectSource() may have been preventing his first ability from working properly.
Nissa, Vastwood Seer//Nissa, Sage Animist - Partly. She should no longer have issues with re-entering the battlefield from exile, the graveyard, or anywhere else when you play your 7th+ land.
Cloudstone Curio - Was triggering upon ANYTHING entering the battlefield, which included Manual Mana tokens. Also corrected it so planeswalkers and enchantments don't allow you to return each other.
Cards not yet fixed:
Ghastly Conscription - Cards were being exiled face-down and then nothing else happened. Now, they're manifested, but under their owner's control. I'm not sure what's going on here.
Melira, Sylvok Outcast - Lingering Tormenter will return with a -1/-1 counter. Couldron of Souls can grant Melira herself or other creatures persist, however, and
they will return properly with
no -1/-1 counters. I have no idea why.
Day's Undoing - May cause the following turn's combat phase to be skipped. I need some confirmation on this, has anyone seen it happen?
Nissa, Vastwood Seer//Nissa, Sage Animist - Apparently can occasionally come into play (if she's been out before) with too many counters. This one could also use some confimration.
Talent of the Telepath - The Spell Mastery ability might be having problems. Another one I'd like someone else to confirm if they have a chance.
The other Origins Planeswalkers may also be having issues. fallenangle pointed out that they remain legendary when they transform. I haven't experienced this, but even if I did, we can't clear supertypes, apparently, so there's not much to be done about it.
These are ALL of the cards I'm aware of that don't work properly (except
Whisperwood Elemental. We'll pretend he doesn't exist...). So, if you know of one I've missed, let me know.