I feel that mine is ready to be submitted.
Here it is, Defiled Wellspring.
Defiled Wellspring
Background: Deep within an overgrown ruin, a wellspring, once pure and untouched, has been conquered by the Marro swarm. Their touch has tainted and defiled the pool, twisting its power for their own gain. What was once an oasis of life and vitality, is now a poisoned swamp. Countless armies of Vipers and Primadon have tried in vain to reclaim the land, but none have succeeded, leaving their treasures for the Marro to claim.
Sets: 1 RotV, 1 SotM, 1 Castle