If you are an aggressive and sneaky strategist, Emerald and Ruby is for you
Lastly, they come into play tapped, which is a significant enough cost to prevent you from running only surveil lands and tends to reward decks that develop at a more casual pace in my experience
It also comes in untapped, so it can go to work right away
For some, its the dream
It's worth noting that while they're bundled together, you can put any Doctor in your command zone with any companion, allowing for all kinds of unique combinations and strategies
For six mana, capable of being reduced down to just one red and one green, Agatha gives your other creatures +1/+1, trample, and haste until the end of the turn