2004-12-01 : Once the token has been created, its power and toughness aren’t dependent on Gemini Engine’s power and toughness, and they won’t change if Gemini Engine’s power and toughness change.

2004-12-01 : The Twin token enters the battlefield as an untapped attacking creature. It’s not subject to any costs to attack or restrictions on attacking.

2004-12-01 : The Twin token won’t trigger any abilities that trigger “when [a creature] attacks.”

2004-12-01 : The token’s power and toughness are set equal to Gemini Engine’s power and toughness. If there’s a Glorious Anthem on the battlefield (which gives your creatures +1/+1), Gemini Engine is 4/5. The Twin token starts as a 4/5, and then the Anthem gives it +1/+1, making the Twin a 5/6 creature.