Entwine is a keyword ability.
Angus is casting One Dozen Eyes and wants to entwine it, to do this he will need to pay in addition to the he would normally have to pay. However, when One Dozen Eyes resolves he will get both, the 5/5 Beast and the five 1/1 Insects.
- 702.41a. Entwine is a static ability of modal spells (see rule 700.2) that functions while the spell is on the stack. "Entwine [cost]" means "You may choose 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 601.2b and 601.2e-g.
- 702.41b. 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.