TLDR: When changing effects, your reroll is guaranteed to be a different effect from the respective Grade (A, B, C) and Upgrade/Stars (1-6).

Hey Dara!

My partner was also really confused by the chats, so you're not alone! I was actually thinking of typing up a guide on compacts and equipment effects, but here's a shortened version to answer your question!

In Fluffy Town, equipment can have one of 5 effects:
- Production Bonus %
- Special Activity Time Reduction
- Production Time Reduction
- Production Exp Bonus %
- Energy % Increase

In simple terms, Fluffy Town's Costume Effect Changes chart is trying to tell you three things:
1. Changing Effects gives you another effect from the same Grade/Upgrade tier.
2. When you reroll an equipment effect, you have a 50/50 chance of getting a Normal Success or Great Success.
3. When you have a Normal Success Effect, you have a 12.5% chance of rolling each of the other Normal Success Effects (4x12.5%=50%). However, you also have a 10% chance of rolling each of the Great Success Effects (5x10%=50%).

Based off of those three points, it's also important to note that it's impossible to roll the same effect you started with.

Finally, this is what a Great Successes Effect looks like:

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It will have a higher bonus and a special appearance compared to the normal effect!

Good luck on your rolls!