New Mob: Marsh Pillager

Marsh Pillagers would act like normal pillagers, but instead of using weapons would drop blocks of mossy mud on people to deal damage (think packed ice style damage.) They wouldn't have any other weapons but would have high HP and instead of 3-5 of them there would be 10 or 15 per outpost which would be a treefort in the marsh. 

They would move extremely fast in water and slower on land. Befriending an outpost would be possible by giving every pillager an emerald.