As it's good to have at least one warlock actively using his brain for this other than shouting nerf and babbling nonsense about hunter mains, there is a bit of an issue. Your nerf idea includes too much done to it, which would result in the problem being solved by ripping away it's viability. What needs to be considered is what can be done that'll keep a reason to use shatterdive without keeping it in its state. The good things to your idea is the take away on damage reduction and putting a target on glacier grenade to acknowledge it plays a huge part in this, but the other nerfs seem like a bit much and the glacier nerf would make it feel a bit too clunky. We also need to consider that not just hunters have this combo and the combo in an entirety is the problem, so Titans need to be considered more openly in the issue. Let me add on an alternative idea that considers your idea for a "start-up" time, but let's make one that keeps it's original uses while lowering its shatter combo strength. I think that in a brief amount of time after the grenade comes up it should have a "hardened" period where it can't be shattered in an instant by any shatter. The idea seems simple and would avoid hurting shatter abilities too much while making the shatter combo not an instant death by giving you a chance to move, and the harden can give it more use as a wall.