(I'm making all the doors open outward unless otherwise noted, just for ease's sake for me
I'm also going to have the creatures fully entered the room, thus "ignoring" Karnage's first post about attacking as soon as the door opened... he should have said that before I posted the encounter)
Karnage erupts in a blur of action, but only the air feels the full force of his fury.
Si'Nat, perhaps thrown off by his savagery, also fails to connect.
Patrick's dagger <thunks> in the doorframe.
Bertrem's blow hits one in the arm in a glancing blow.
Rondo's swing also slices through air.
Cugel fires an arrow that shatters on impact against one's body.
Round 2 - You have the initiative (I'll assume you keep attacking since nothing in the situation has changed; i.e. someone wounded or dead or whatever)
Karnage redoubles his attack but to no avail; his blow is agilely dodged.
Si'Nat's sword is met in mid-air by his opponent's mace.
Bertrem's swing goes wide.
Rondo still fails to connect.
Cugel finally draws a thin line of blood as his arrow scrapes by one's head, throwing back his cowl and revealing human features.
(Not sure if Patrick wants to throw another dagger....)
Finally having a chance to attack, one swings at Karnage and one at Si'Nat and both hit but fail to penetrate the armor and thus deal damage.
Round 3 - You have the initiative again.
Karnage and Si'Nat fail to get past their opponent's guard.
Bertrem can't do much on his end either.
Rondo, with a mighty blow, finally cleaves the one hit by Cugel in half.
Cugel's arrow flies wide.
The one facing Si'Nat scores a glancing bruise.
Round 4 - You win the initiative again.
Doing a fair imitiation of Spiderman, the creatures weaves, ducks, and blocks everyone's blows. However, he can't do much in return either.
Round 5 - You win initiative again.
Everyone fails to hit each other again.
Round 6 - You lose initiative (finally

)
His blow is again deflected by Si'Nat's armor. Everyone else misses except for Rondo, who manages to carve a big chunk out of his chest with his axe. Spurting blood, the creature falls to the floor.
(Whew! I gotta say, only Rondo's +3 bonus due to his strength got you through that one
)