Rain of Frogs is an epic spell that randomly spawns a number of 1 strength Toads. The number of toads spawned and the cost of the spell can be upgraded when leveled up. Rain of Frogs works well in toad decks.
Rain of Frogs can be used to bring lots of units to the board at once. Sometimes they can support you, sometimes they can support your enemy.
Rain of Frogs can be useful for blocking tiles that your opponent could be using to play cards. Likewise, Rain of Frogs can clog up your available space to place units and structures.