Prismatic jelly is required to complete the Prismatic Jelly wizard quest you get from the special order board; here's how to quickly and easily find the jelly in Stardew Valley.
How to find prismatic jelly in Stardew Valley
To find prismatic jelly in Stardew Valley, you will need to find and kill a prismatic slime; however, this is easier said than done. This is because prismatic slimes are a rare type of slime that only spawns from 95-115.
That said, make your way to the minds and start your search from 95 and down; you will want to find a slime that is rapidly changing colors. If you see this down in the dark, congrats, you have found your prismatic slime. Kill it, and it will drop the jelly, and you will then be able to complete the wizard quest.
As a side note, you might not want to accept this quest if you haven't explored the mines or if you don't intend to complete it after accepting it. This is because you will have only seven days to complete the quest; due to this, the quest may prove too enduring for new players.
Related: how to make wine in Stardew Valley
To complete the prismatic jelly quest, you will need to go and find the wizard over at the wizard tower location, as shown above. Once inside, find the wizard, and then select the option to turn the quest in. Upon completion, the wizard will give you 5k gold and the option of either an obelisk or monster musk, as a side reward.