Luck and unluck potions do not have effect on anything. What I mean by that:
They do not affect the dungeon loot,
They do not affect fishing,
They do not affect mob drops.
Here is a video by Xisumavoid testing the luck & unluck potions:
https://www.youtube.com/watch?v=d6RsmSSXs9g
Also, you can't make them in survival, and in mapmaking and do not see anything too useful for them that you couldn't already done. This part is more like a missing feature, so I posted it on the Minecraft Suggestions Reddit:
https://www.reddit.com/r/minecraftsuggestions/comments/4785k7/luck_unluck_potions/
Thank you!
Comments 3
I haven't seen too much difference between the fishing either. I don't know, if they work or not, but they should definitely do something about them.
The do affect fishing, as Xisuma showed, and that's all it's set up to affect with the default loot tables. No bugs here.