Polluted Runoff

({t}: Add {b}, {u} or {r}.)
Polluted Runoff enters the battlefield tapped.
{t}{3}: Sacrifice Polluted Runoff. Search your
library for a basic swamp, island and mountain
and put them on to the battlefield. Shuffle.
The byproduct of the township's industry
is the source of conflict with those that dwell
in the hinterlands.