Rotigus

Rotigus the Generous One is the Rainfather, a Great Unclean One who gifts abundance until abundance is a drowning. He was second in Nurgle's heart until Ku'gath disobeyed and died on Iax. Rotigus took the chair and made sure the loser heard about it.

He rains on maiden worlds, on hive worlds, on anywhere a harvest can rot into worship. Harlequins of the Frozen Stars once danced his flood back into clean water. Vigilus saw him during the War of Beasts. Macragge saw him in the Library of Ptolemy, tempting a historian toward Imperium Secundus with a smile full of flies.

He does not need a cauldron to end a civilisation. He needs a wet season and an audience that says thank you.