Aang's Iceberg

If Aang's Iceberg leaves the battlefield before its triggered ability resolves, including if it is sacrificed by its activated ability, the target permanent won't be exiled.

If a token is exiled this way, it will cease to exist and won't return to the battlefield.

If an Aura is exiled this way, its owner chooses what it will enchant as it returns to the battlefield. An Aura put onto the battlefield this way doesn't target anything (so it could be attached to a permanent with shroud, for example), but the Aura's enchant ability restricts what it can be attached to. If the Aura can't legally be attached to anything, it remains in exile for the rest of the game.

The third ability of Aang's Iceberg allows you to sacrifice Aang's Iceberg as the ability resolves, not as a cost to activate the ability. If Aang's Iceberg leaves the battlefield before the activated ability resolves, you will be unable to sacrifice Aang's Iceberg and will not scry, even if Aang's Iceberg was sacrificed via a different ability while its activated ability was on the stack.