The zombies seem to be strengthened by the blood soaking the area from Zook and the guardsman. Rethlin cannot channel enough of the Flame to affect them.
The guards James has brought waver: one of their number is dead, there's lots of zombies, there's a wizardess exploding zombies with her little finger, and James didn't bring them that many crullers.
Then James shouts "Over the top, boys! Are you going to be outfought by a librarian?" and galvanized by a professional rivalry, they move forward and attack, pairing off to attack each zombie two to one with their halberds.
The first pair of guardsmen make devastating hits on their zombie, leaving a shredded remain standing only through a few last threads of magic (Not down, but badly damaged).
The second pair follow their example (Ditto).
The third pair is James and the fifth watchman. The fifth watchman cleaves the zombie along its spine. James leaps forward with a short sword to finish it off, drives the blade into the zombies kidney, and pulls it out. It leaves a small hole but does not inconvenience the zombie at all.
"Uh-oh." he replies, looking lamely at his sword.
Manticore snarls as his zombies are slashed to ribbons, then takes up his crossbow to even the score.
His first shot is at Zook.
Zook shot (1d20+8=28, 1d10=1)
Critical threat
Critical confirm, damage? (1d20+8=19, 1d10=6)
Not confirmed, between mage armor and firing into a melee.
Manticore's bolt slides through the gap a halberd just ripped in a zombies torso and pierces Zook's left eye.
Zook totters, nearly dead on his feet, but still defiant. (0 hit points: you are still conscious, but if you do pretty much anything but move 5' or heal yourself, you lose a hit point and fall unconscious, bleeding out.)
"Dang..." whispers one of the guards in silent admiration. "What a stud!"
Manticore stands in slackjawed amazement and takes a second shot at Rethlin, but his hands are beginning to shake as the unkillable librarian gnome shakes his courage.
Manticore on Rethlin (1d20+8=13, 1d10+2=3)
"
It's n-not p-possible..."