The protection it gives your other merfolk pushes it ahead of the Emperor
To clarify this just in case, that doesnt include any buffs like counters, just the creatures original stat for power unless changed by something that redefines that power above 1, like Harmonious Archon or the creature has a variable power, like equal to the number of lands on the field
We should be excited to see this card in action, and also start devising ways to counter it
White-Black Sacrifice Victory requires sacrifice, and white-black takes advantage of this by turning your permanents into a resource
In short, to keep Magic: The Gathering fresh you have to play it competitively, in draft formats and playing within a single set or at least within the current standard (the last 3 sets + the core set for the year) In comes MTG: Arena
Read our step-by-step pillar guide, How to Build a Commander Deck, and our breakdown of the best ways to build a Commander deck