Commons dont tend to be expensive, but they can be quite powerful
This is achieved by spreading +1/+1 counters all around your creatures, doubling them to easily swing out at all of your opponents
In all seriousness, though, a panic button available to any deck is something to be wary of, and its appreciated that designers were mindful to limit the potential for annoying scenarios by making this legendary and having it exile itself on activation
The difference is that the land goes into your hand if no one controls more than you, similar to Scholar of New Horizons
You need a non-toy creature to get the first half rolling, after which you can stockpile creatures and fire off the 6-mana room when you're ready
Includes Jhoira of the Ghitu, Stormtide Leviathan, Desolation Twin, Tromokratis, and dozens of other powerful creatures and spells