Landed on Eldar Falcon squad where I draw two yellow threat.

Frist threat: Alluring daemonette "At the start of your engagement phase, you may draw 1 corruption to immediately take this enemy as a trophy"

Second threat: Emperor children's noise marine: "You cannot use armour during this battle & if you win this battle gain 1 influence"

My question: They are both yellow therefore I battle these together. BUT, how can i use the Alluring daemonette ability? This would split the combat into 2 actions: first pick the daemonette for free (with a corruption card) and then battle the Noise marine.

Not sure. I battled these two together and won the combat, so it was a mute point. But still I would like to know how to handle Alluring Daemonette when there is another yellow card on the space.

Many thanks.

The key expression is here is "at the start of your Engagement phase" which occurs before the start of battle, so you can take a corruption card to immediately defeat the Daemonette and take her as a trophy and then proceed to battle the remaining cards.

I thought as much. You are right that the "at the start of the engagement phase" is the critical point. In a sense, I defeat the daemonette during the pre-battle sequence.

That makes sense. Thanks.

Not even the pre-battle sequence. You can defeat her even if there is no battle (for example if you Evade all enemies).

On a slightly related note, there's a tricky situation with Threat cards on spaces with text boxes(like Antian Shrine World, for instance.). Note that if you evade all Enemies on such spaces, you still cannot resolve the text box, since you are forced to interact/engage with the Threat cards.

Evasion is considered part of that engagement.