Not exactly the worst legendary I crafted but the worse one that I crafted recently: Sherazin, Corpse Flower. it dies so fast and to bring it back it requires overcommitting your cards .seriously 4 cards in 1 turn is too much even for miracle rogue. I'd rather the condition is after playing 7 cards not 4 cards in one turn.
In Kobolds I crafted both The Last Kaleidosaur and Lynessa Sunsorrow on a whim for a deck I would end up playing maybe six times before tiring of its crappiness. To be fair I was working a dream job at the time where I was making around $300 a night. I still have them.
both obviously very deck specific minions, that require tools to cheat them out earlier somehow. In my case I thought Strength in Numbers or Zerex Cloning Gallery would get the job done, but I'am still not shaking off that feeling of a fail Investment.
Prince Keleseth crafted this after watching some Trump videos, never got the same results
Deathwing, Dragonlord Thought it would be insane in a dragon deck but it just gets polymorphed or hexed...
If I remember correctly, Trump used Prince Keleseth some kind of control Mage deck, which is not what it was ever meant for, it's for aggro decks and it's fine in those, so you just need to look at him from a different angle
Archivist Elysiana- seemed like a good craft and it just sat in every control deck I played. I've crafted bad cards, played them, and found out that they were bad. That's one thing but I crafted her and never played her once. She just sat in my deck or hand- I know I was probably playing her wrong but WOW what a total waste of 1200 dust (created and dusted).
Worst thing I ever crafted by far was Kazakus. 1600 dust and I literally used it in 1 game because although hes extremely powerful and a fun card to play, I HATE playing warlock/mage reno decks and very quickly realized that, so I never felt the need to play him again. It's a real shame he wasn't neutral because reno's decently fun and interesting in classes like shaman, rogue, druid, and paladin because you don't gimp your deck at all with mage and warlock since the 2 classes both have numerous AoEs and removal that do the same thing but are different cards.