- Potion works as intended; its user becomes blind for 1d12 minutes after the potion's effect ends.
- Potion makes invisible only for the particular type of enemies. Roll 1d6: 1-3 living creatures, 4 demons, 5 undead, 5 unliving (golems, automatons etc.).
- In addition to invisibility, potion's user begins to glow. I guess it's possible to miss it in broad daylight.
- In addition to invisibility, potion's user starts to stink horribly (CHA halved, beings possessing acute sense of smell may be able to detect him/her with relative ease). This side effect lasts until the next full moon.
- Potion works as intended, but first three creatures with level / HD lower than the potion's user become invisible for him/her.
- Potion's effect kicks in with significant delay (4d6 hours!).
- Potion was mixed with another magical potion (determine randomly), duration / potency of both effects is halved.
- Duration of invisibility is doubled - as well as all damage received by the potion's user for as long as he/she remains invisible.
- Duration of invisibility is tripled - but each turn of its effect the user must save vs Magic to avoid giggling uncontrollably. If natural 1 is rolled during the saving throw, the porion's user starts to laugh so hard that he/she is unable to perform any other actions this turn.
- This potion seems to be perfect - invisibility lasts forever. Each morning, potion's user must save vs Magic to become visible for the next 24 hours. This effect can be dispelled by a high-level wizard / priest. Or divine intervention. Or infernal contract.
Also, back in 2012, I made something similar for the Potions of Invisibility.