"We need to get out of the open!" shouts Hakon, looking for any kind of physical feature the party (or at least, he himself) can use to guard their backs and limit the things' attacks. He readies himself for combat, knowing that the attack will come.
Orofer shoots the lead snake with his crossbow (20 hit, 3 damage).
Everyone gets into cover, with Sporglebiff diving into the first big clump of grass. The serpents ignore Sporglebiff and head towards the main group who have taken cover among the willow trees. This slows the snakes down enough to give you a bit more time to react.
Now in a somewhat defensible position among the trees, Hakon takes advantage of the fact that the enemy's approach can be hampered. He stands firm alongside Rutgar with axe and shield, ready to defend the artillerists and spellcasters should the creatures get within his weapon's reach.
Ok, in interests of moving along, I will assume Brother Cyril takes cover also.
Initiative is tied (PCs 5, serpents 5)
The serpents attack those standing and fighting, due to the cover, only three serpents are able to attack. Rutgar and Hakon may attack the same one if desired. The injured one has held back somewhat, but could still be a target for Orofer.
Quasmus, Amadeus, and Brother Cyril all take cover among the roots and underbrush. Sporglebiff is able to find a bit of a depression to get more fully hidden.
I will resolve attacks once everyone declares target.