Because targets are chosen as you cast a spell, you can't have Inscription of Ruin return a creature card and then destroy that creature.

If a card in a player's graveyard or a creature on the battlefield has in its mana cost, X is considered to be 0.

If you kick Inscription of Ruin, you can't choose any one mode more than once.

If any targets become illegal, the other targets will still be affected as appropriate.

If more than one mode is chosen, perform them in the order written. Nothing can happen in between, however, and no player may choose to take actions. Any abilities that trigger will be put onto the stack after the spell has finished resolving.

The kicker ability doesn't let you pay a kicker cost more than once.

If a spell's kicker cost was paid, the spell is "kicked."

If you copy a kicked spell on the stack, the copy is also kicked. If the copied spell is a permanent spell, the token the copy of that spell becomes when it enters is also kicked.

To determine a spell's total cost, start with the mana cost (or an alternative cost if another card's effect allows you to pay one instead), add any cost increases (such as kicker), then apply any cost reductions. The spell's mana value remains unchanged, no matter what the total cost to cast it was.

If a card or token enters as a copy of a permanent, the new permanent isn't kicked, even if the original was.

If you put a permanent with a kicker ability onto the battlefield without casting it, you can't kick it.