What I'd like to do is make is so that when a player picks an item up a monster spawns and targets the player carrying the item. The monster should be able to reveal the player if hidden (to foil would be stealthers). If the monster is defeated, I'd like all the poison traps in the room to be activated to make it difficult for the player to make it out alive. Any thoughts on how this could be done?

Hmm if you mean a custom item, there is nothing easier. You can do it perhaps 2 possible ways, the first is with TriggerOnCarried and the second with IF condition.

So.. setting triggeroncarried -> firstly you've got to set Min/MaxD to zero, ProximityRange>0, ProximitySound=-1 (i dont like that sound ) refract.. perhaps from 5-10m for your case and finaly set the TriggerOnCarried.. for example this way -> Abracadabra's pants, ShortPants ...(name, type) or whatever you want..

hmm damn i see, there will be the same problem that I have with getontrigmob


1 IF/GETONTRIGMOB,Hidden=True/33/44
1 GOTO/1
33 SETONTRIGMOB/Hidden/False/EFFECT,14120,20/SAY/*{GETONTRIGMOB,name} has been reveleated!*
33 Troll/Combatant/TRIGMOB/Location/{GETONTRIGMOB,Location}
44 Troll/Combatant/TRIGMOB/Location/{GETONTRIGMOB,Location}

than you can create the second spawner, which will spawn the poison traps..
spawn settings:

Max/MinD = 0, ProximityRange>0 Refract something between 5-10m (or better, you can set the refract according to first spawner RefractoryOver perhaps with annother entry in first spawner like
33 SET,serial of second spawner/RefractoryOver/{GET,serial of first spawner/RefractoryOver}
and also for sub 44), than set the TriggerObject as a first spawner and TriggerObjectProp to KillCount=1, Group=True, and dont forget on Duration (in your case I recommend you to set it on 2m) which will delete the poison traps after 2m from spawn... finaly set the syntax like

GasTrap/Visible/false

ok.. I've tryed it... and ok

.. hope i helped..