United in Stormwind Cards List & Guide
The new Benedictus card includes Mind Shatter as a "related card". Currently playing a second Shadowform just refreshes your Hero Power instead of giving you Mind Shatter which deals 3.
If they're pushing Shadowform as a strategy in United in Stormwind, maybe Mind Shatter will return?
I think it would be a cool idea. I mean, Mage already has Wildfire and it's something similar. Kind of funny, but playing Shadowform actually makes no sense with Benedictus.
I really hope this is the case, but Shadowform itself also had Mind Shatter as a related card since the core set came out.