Cumulative upkeep {1} (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.) Flow of Maggots can't be blocked by non-Wall creatures.
"The very earth seemed alive and made a sound like the writhing of the damned."
—Lucilde Fiksdotter, Leader of the Order of the White Shield