Siren of the Fanged Coast

Flying is an evasion ability.

A creature with flying can’t be blocked except by creatures with flying and/or reach. A creature with flying can block a creature with or without flying. (See rule 509, “Declare Blockers Step,” and rule 702.17, “Reach.”)

Multiple instances of flying on the same creature are redundant.

Tribute is a static ability that functions as the creature with tribute is entering the battlefield. “Tribute N” means “As this creature enters, choose an opponent. That player may put an additional N +1/+1 counters on it as it enters.”

Objects with tribute have triggered abilities that check “if tribute wasn’t paid.” This condition is true if the opponent chosen as a result of the tribute ability didn’t have the creature enter the battlefield with +1/+1 counters as specified by the creature’s tribute ability.