The addition of the new spells is fantastic, but darkness, grasping mire, and life drain ALL end the moment you cast ANY other spell - even simple ones like fionn's wrath and immolation.
This is keeping a magick build from being on par with other builds, and it also makes the playstyle feel substantially worse than it should.
Some more things I've noticed are that Bramble Wall, Quake, and Arborist's Shield also do this. Additionally, Ring of Empowerment and Dispel... just don't seem to work. I'm not sure if I'm using Dispel wrong, but Ring of Empowerment just doesn't boost my damage output.
On the opposite end of the spectrum, Summon Swarm is absolutely broken. While other DoTs like Hermetic Flame wear off after a little while, Summon Swarm simply doesn't do that. It even goes through the harpy queen's shield.