Morph, Space Goo Emerald is already considered one of the best colours to play if you like using Lorcanas Floodborn Shift mechanic, which is the ability to play character cards for cheaper by putting them on top of a character with the same name that you already have in play
Theres a lot of discussion online about the optimal number of turns to pay into Mystic Remoras cumulative upkeep, and the answer really depends on the situation
It's notoriously difficult to track sometimes, but it can also just end the game immediately and prevent having to do too much math
Im only selling if someone at my local shop is willing to overpay a little
If youre playing white or black, you need an exceptionally good reason to not be a Lurrus deck
Being blue and not having Flying definitely restricts the range of homes the card can show up in, hence why it isnt higher on the list