Entwine

Entwine is a keyword ability appearing on modal instants and sorceries; i.e., ones with the "Choose one —" clause.

Description
As you cast a spell with entwine, if you additionally pay the entwine cost, instead of choosing only one of the modes of the spell, you choose all of them.

Spells with entwine were featured in the Mirrodin block. Mark Rosewater came up with the mechanic in his sleep.

Entwine was also used in Modern Horizons and Commander 2019.

Rulings

 * You decide whether you're paying the entwine cost as you cast the spell.
 * If you choose not to pay the entwine cost, you can choose only one mode. If you choose to pay the entwine cost, you choose both modes.
 * If you pay the entwine cost, choose targets for both modes as you cast the spell. When the spell resolves, follow the instructions in the order they're written.