: The Letter "R"
Tomorrow I am surely here, yesterday I am found as well. Today I am gone. Who am I?
Half of me builds towers and cities, the other half is squirming in the dirt. When I am whole, I become angry and bitter. Who am I?
I am found atop the mountains, and alongside a crag. At the end of a winding staircase, and I will accompany the plague. Who am I?
Half of me will mend, the other half will imprison. When I am together, I will poison. Who am I?