If the target enchantment you control leaves the battlefield or otherwise becomes an illegal target before Calix’s second ability resolves, the target permanent you don’t control won’t be exiled.

Auras attached to the exiled permanent will be put into their owners’ graveyards. Any Equipment will become unattached and remain on the battlefield. Any counters on the exiled permanent will cease to exist. When the card returns to the battlefield, it will be a new object with no connection to the card that was exiled.

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

If an Aura is put onto the battlefield without being cast, the Aura’s controller-to-be chooses what it will enchant as it comes back onto the battlefield. An Aura put onto the battlefield this way doesn’t target anything (so it could be attached to an opponent’s permanent with hexproof, 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 its current zone.

If an Aura is being put onto the battlefield at the same time as an enchantment creature, that Aura can’t enchant that creature.