I will try not to spoil what Jellyphish (relic) does.
In act two there is the colosseum event. Within this event-floor, combat starts twice. Since Jellyphish activates on each combat start but only removes its "gift" at the end of the floor (once) you are granted one unintentional permanent "gift". This issue likely occurs with any other floor where there are multiple combats, but this is the only event that comes to mind in the vanilla game and the only one that I have seen.