I'd grab a pen and have some paper handy to write on so that if you need to make notes about things that are harder to track because they aren't as visible ("Okay, I have his Teferi's Protection exiled with my Spelljack" or "Erin's graveyard contains three cards she can cast from the graveyard"), you have easy access to doing so
Whenever Grimgrin attacks, it can destroy one opposing creature to generate value, and get another +1/+1 counter
For the sake of simplicity, think of a set as being split in five colors (yes, there are colorless cards, but let's ignore them for this example)
The way its cards chain together makes it that smidge more complicated than the Amber and Sapphire deck above, so its recommended for those players who already know the basics of Lorcana and are looking to dive into its more advanced strategies
Add Curiosity to join Niv-Mizzet, the Firemind
More specifically, many fans are paying well over the odds to get the normal One Ring card because it's so powerful