While Sera flew around, suffering the attention of both powerful creatures, Faith moved everyone else to a few hundred meters away. They watched the Sera for a few seconds before beginning to decide upon a quick plan.
There weren't many resources they could use. None of the six people gathered atop the tree branch had purely offensive powers.
Cass, as a Stellar, was the most powerful, but her illusions were awful at offense. Astrid could buff and defend her friends, but she couldn't attack. David's ability was similar to Jörmungandr's, but a lot weaker, making him the most useless.
Melinda, Faith and Lilith could actually attack. However, physical attacks seem useless against the enormous snake. Only Lilith remained with the ability to damage the World Serpent.