If Arwen, Weaver of Hope and another creature you control enter the battlefield at the same time, Arwen's ability won't cause that creature to enter with additional +1/+1 counters on it
This would be a good effect on its own but is made even better by both her color identity, as red and blue generally have a strong focus on casting, and her second effect, allowing her to exile and assign spells to attractions, copying them each time the player visits them
Mystic Remora Now well go from one homonym to another, much like miter/miter, and even more so than the previous example, people can be forgiven for not knowing the dual definitions of remora. The famous fish-thats-not-a-fish has been imposing taxes on Magic players since Ice Age, and thats a long time for people to wonder why an enchantment clearly depicts an aquatic critter, and not, say, some glowy lights like most enchantments
If money is changing hands, that's a whole other kettle of fish
The Explorers found their ancient enemies spawning everywhere
The rest of the text is just a bonus on top of an already solid combination of abilities