In order for the Warseeders to create the Warfront Anicents they must infuse the seedlings with water that has been cursed by their Wardens in Asheran. If you are able to slip in to the camp where this water supply is located and taint it then their ability to produce these abominations would be halted. Our reports tell us that there are two Jungleheart Wardens guarding the well. Kill them and then do what you must in order to stop the Warseeders from creating any more Warfront Ancients.