Rain Nerf 7/15/15 Patch, Among Other Things

[Sancus]

They're still more efficient than Spears by a long shot. And depending on the mods on you at a given time, a lineup with Rains actually can be about equal DPS to (or ahead of if you have no mods) one with Spears (as your crit chance increases, Spears pull ahead). Under burns definitely don't use rains. If you have mana issues or you lack ADPS, a rain lineup may still be worth having on certain fights.

Essentially they're now a very niche/situational spell.