In Dragon Pass, Heler is generally associated with the rains that are released when Orlanth defeats Aroka. He’s a step up from “Lightning Boy” (the tiny cult dedicated to worshiping Orlanth’s lightning bolts) but his cult is less than 1% of the adult population. He’s of cosmological importance, but lets face it, Orlanth Thunderous is a more useful overall cult – unless your goal is to specialize in bringing in the rain (Orlanth Thunderous does that too, but the Flood spell is pretty cool!).
Heler is a more important deity within the context of the water deities than among the Orlanthi. Among the Orlanthi, he’s Orlanth’s sidekick, the Rain God, the embodiment of Orlanth’s fertilizing rain. His cult is small, as he provides his most useful spell to Orlanth Thunderous. Like Mastakos, he’s largely worshiped as part of the Orlanth cult. But among the water deities, Heler is of great cosmological importance, if little cult importance. He is the half-brother of Magasta, the child of Sramak and Daliath. He’s the father of King Undine and the grandfather of all those water elementals, nymphs, etc. He is Water in Air, and loads of other remarkable things. But among the triolini his cult is miniscule. And what need to the merfolk need of summoning rain?
Heler’s most important child is the entity the God Learners called King Undine. Together with Mirinitha, King Undine is the sire of all water elementals and water nymphs. And through Warera the Water Nymph, Heler is the great-grandfather of Malkion!