Red Suns Twilight is probably my favorite spell of the cycle
Much as I yearn for larger sets and the replayability they enhance, bonus sheets reskinned reprints that appear in about a third of packs do take the edge off
Adrix and Nev, Twincasters Adrix and Nev, Twinscasters is another popular Merfolk commander, but this one certainly doesn't need you to be in a dedicated Merfolk deck
Dedicated control decks are where it can struggle to win as the key spells can be denied and mass removal sorts out everything else
I really love Thaumatic Compass as an early play / mana sink that makes sure we keep hitting lands -- in a deck with 12mv spells this is important -- and then doubles as protection, Wandering Archaic slows down opponents or generates value early on, Stonespeaker Crystal is a great ramp that doubles as powerful GY hate when needed
Urzas Saga and Force of Vigor Here we have what might be the single best threat in the format, which is also a spread of answers, and the answer that in turn caps what would otherwise be a true dominant force in Modern