Multicast and Verdant Spheres

Multicast works on Verdant Spheres which I think is fine but I don’t think it should be affecting the 3 spells that it casts off the target’s gems. With the rune that adds +1 to spells cast with Multicast you can cast an amazing number of spells. (3 Verdant Spheres for a result of 9 spells cast with multicast = 30 total spells cast) It even seems to bypass the 15 spells per turn limit.