User blog comment:GreenMoriyama/Izo, the Blizzard Prince/@comment-1330314-20160405115322/@comment-1330314-20160411104125

I'm looking forward to what you have in store for Izo in the future. In the meantime:
 * Perhaps there's a way of keeping sustain on Crushing Bolverk, though it would likely have to be implemented very differently (I'd also really avoid making it apply on minions unless there's a very, very good gameplay reason for that to happen). Personally, I dislike having a shield and a heal on the same kit, because both usually tend to have the exact same purpose and are thus going to be competing for power on your champion's budget.
 * Grounding is a new type of crowd control briefly shown on leaked rework, and prevents affected enemies from using dashes or blinks. I think it could be appropriate on Izo, since it'd give him some sticking power appropriate for an ice-based control fighter.
 * The reasons you gave for Field of Rime's effects are justified, but the implementation is still fairly underwhelming. I'd still recommend a different effect, even if it achieves the same purpose. I wouldn't discount the ice rink mechanic just yet, but if you don't like it, there are likely many other different effects that could work as well (for example, you could turn Field of Rime into a massive AoE root).