Herald's Carapace (Hypothetical Zhonyas replacement)

So if you've been over on the Gameplay area of the boards, you've seen that Zhonyas is quite the topic of discussion. Its active and stats are very powerful, but that active is so powerful that its build path and cost are rendered clunky and frustrating. I've actually seen some comments suggesting its removal if it's so problematic, replacing it with an alternative.

Herald's Carapace + + 850gp (2900 total) -100 AP -50 Armor ACTIVE: Void Shield: Generates a shield that absorbs up to 300 (+70% AP) damage for 3 seconds. As long as the shield persists, this champion is Silenced. (90 second cooldown)

The idea behind this is quite honestly making a somewhat watered down but still effective version of Zhonyas, which isn't burdened in its cost so massively because of its extremely powerful active. Void Shield gives mages the on-demand protection they seek while still being able to move and react, but at the cost of being unable to cast spells. This means it's not an on-demand "I win the duel" spell but rather a means to survive bad positioning or being focused down. Due to the silence it also wouldn't need to be balanced with particularly synergistic champions in mind, like Swain, Morg, or Fiddlesticks.

Hypothetically this gives enemies a lot more room to play around the active as well, especially in teamfights; do you focus down the target, trying to eat through the shield and returning their ability to cast spells in exchange for the potential to take out a squishy, high-priority target? Or do you change target focus and put your attention on the rest of the enemy while their mage is unable to contribute to the fight? Or perhaps you simply keep them locked down and wait out the shield before dropping everything on them.

Thinking more on this idea I know it's not ideal, but... it's a thought. Don't judge too harshly, if possible?