The monster loses 50% health but continues its attack.
Otherwise, it would have killed the one it was heading towards. Or, a trap was set near it; it initially destroyed it, and then killed it. And the mages were infecting. But where are the Necromancer's blockades? Maybe it just wasn't using them?
Added 2 minutes later
It seemed to me that the guards walk together towards one target.
They cannot protect each other.
