“ A casual remark by one of the party about something met on a previous adventure leads to a summons to and grilling by the Mages' Guild (or equivalent), probably resulting in an expedition back to that area to recover the things for study by the Guild. The party's presence will be 'requested' for this expedition.”
“ The PCs are exploring the catacombs beneath a Colosseum-in-Rome type of structure, when they come across a foul-smelling, stagnant, ankle-deep with algae, public mass latrine. Countless urinals of marble, line this rather large chamber equally crafted of marble. Whatever system of plumbing once worked here, has not in many years. Old graffiti lines the stained,dirty walls, prominently bolded are such intellectual poetic musings as, 'Urine For It Now', 'I Pee Therefore It Comes' and 'Now Urine Trouble'.
A few moments after the PCs get to take in this unpleasant location, they hear the low rumbling of ancient plumbing and rather large Urine Elemental rises like a great, wet, wave of filth to attack them. The creature reeks and exudes noxious debilitating fumes, while its liquid strikes burn flesh like acid.”