Does copying a spell with an additional cost like kicker mean the copy also has the kicker effect?

When you copy a spell, the copy is created as an exact copy of the original, including any choices made for that spell — such as whether kicker was paid (CR 706.10). This means if the original spell was cast with its kicker cost paid, the copy is also considered to have had kicker paid, and will receive the kicker bonus effect.

However, the copy itself is not 'cast' in the traditional sense — it is placed directly onto the stack (CR 706.12). This means you do not pay any costs for the copy, including the kicker cost. The copy simply inherits the paid/unpaid kicker status from the original spell it was copied from.

The key rule is CR 706.10: 'When copying a spell or ability, the copy retains the choices made for the original, including modes, targets, and whether additional costs like kicker were paid.' So the copy mirrors the original's kicker status automatically.

Example: You cast Roil Eruption with kicker paid (by paying the extra cost). An opponent uses Twincast to copy it. The copy of Roil Eruption is also considered kicked, so it deals 5 damage (the kicked amount) rather than 3, even though no additional mana was paid for the copy.

If you copy a spell that was cast without kicker, the copy also lacks kicker and will not gain the bonus effect. The copy always mirrors the original's state at the time of copying.