Overall good changes, but:
In addition, shamans will no longer spawn thralls if they are poisoned or envenomed, giving everyone a bit of a break.
Does this mean that Shamans will start firing mage attacks when poisoned rather than summoning? Or do they just completely stop doing anything?
Correct, they will start swapping to magic. Poisoned shamans now no longer spawn thralls, this means that they're now vulnerable to poison which means that players can tag them and forget about them, which should help them control the flow of the room.