Other reviewers have rightly pointed out how this is a good card, with the backlash effect being less likely to occur on hard/expert.
However, I can't say I like the card design. Mystic have traditionally been powerhouses when they got all their spells set up, but getting there is not always that easy. I think part of the "charm" of mystics is the somewhat swingy behavior.
Before the release of this card, if you wanted to supplement Shrivelling, you had to include situational or somewhat iffy cards like Song of the Dead, Shards of the Void, Wither or Storm of Spirits. Now you can just include this. It's the equivalent of having 4x Shrivelling in your deck, and Azure Flame has all of the upgrades too. I frankly don't like this.