Why do monsters attack certain targets?

[Wyrm]

Everything in the game has a threat rating, which determines the order they're attacked in by NPCs/monsters. I remember there being a topic on it sometime ago, but don't remember all of the details. I think the way it worked was that players had a threat rating of 10, mercs/minions 7, decoy 15, and monsters affected by attract of something higher than decoy. Bear in mind that the actual numbers are probably wrong, but I think they're accurate in the threat order.

I'm not sure if there are attacks that will change your threat rating, but it seems likely, considering how monsters will go after Fire Golems and Holy Freeze mercs after even if there's a higher threat rating something around.

Also, once a monster/npc is locked onto a target, it'll stay on that target until it attacks or something interrupts it (ie casting a minion summoning spell so that it will run into it before it gets to you, or being hit by holy fire and the like), then it'll go to the closest target with the highest threat rating.