Entwine

From MTG Salvation Wiki

Entwine is a keyword ability appearing on modal instants and sorceries, ie. ones with the "Choose one —" clause. As you play a spell with entwine, if you pay the cost associated with it, instead of choosing one of the modes of the spell, it functions as though you chose both.

Spells with entwine were introduced in Mirrodin.

From the Comprehensive Rules: 502.32. Entwine 502.32a Entwine is a static ability that functions while the spell is on the stack. “Entwine [cost]” means “You may choose to use all modes of this spell instead of just one. If you do, you pay an additional [cost].” Using the entwine ability follows the rules for choosing modes and paying additional costs in rules 409.1b and 409.1f–h. 502.32b If the entwine cost was paid, follow the text of each of the modes in the order written on the card when the spell resolves.

[edit] Example

Betrayal of Flesh - Instant Choose one - Destroy target creature; or return target creature card from your graveyard to play. Entwine-Sacrifice three lands. (Choose both if you pay the entwine cost.)

[edit] Rulings

• You decide whether you're paying the entwine cost as you play 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 play the spell. When the spell resolves, follow the instructions in the order they're written.
• For all modal spells that don't have entwine, you can choose only one mode. Only the entwine ability allows you to choose more than one mode.