“ Temple of some malign being invites you warmly and offers help (curing,needed spell etc) for some minor sacrifice . Sacrifices must be everytime bigger to work - up to living inteligent creatures. Maybe you pay some other price,too...”
“ As they travel they notice a horrible rotten smell. As they travel it gets stronger and stronger forcing them to cover their noses and mouth less they choke on the horrible smell. Rotting animal carcass that has been ripped apart and tracks all over, covered in maggots.”