Outermost Edifice

({t}: Add {r} or {w} or {u} or {b}.)
As Outermost Edifice enters the
battlefield, you lose 3 life.
"Artificer's journal, Day 731. The constructs are
still harvesting mushrooms from the undercity
and our phytoplankton levels in the river are
now in balance. Definitive: trees are overrated."