Zevlor, Elturel Exile

Like any spell, each copy will check to see if its target is still legal as it tries to resolve.

If the spell has an X whose value was determined as it was cast (like Fireball does), the copy has the same value of X.

Zevlor, Elturel Exile has received an update to its Oracle text. The word “only” was inadvertently left off the printed card. The updated text is included above. Notably, an instant or sorcery spell with multiple targets will not cause the delayed triggered ability to trigger, even if only one of those targets is an opponent or an permanent an opponent controls.

If the spell is modal (that is, it has a bulleted list of choices), the copies will have the same mode(s). You can't choose different ones.

When the delayed triggered ability of Zevlor, Elturel Exile resolves, it may create one or more copies of a spell. You control each of the copies. Those copies are created on the stack, so they're not “cast.” Abilities that trigger when a player casts a spell won't trigger. The copies will then resolve like normal spells, after players get a chance to cast spells and activate abilities.

As you make your choices for each other opponent, you can choose that opponent or any permanent they control, but if the chosen player or permanent isn't a legal target for the spell, the copy won't be created.