Only one of the slates has any writing on it, but you cannot make out the words: perhaps they are in a different language or some sort of code. It is partially erased.
Maeglin motions for you to bring it over so he can attempt to read it (
secret roll, SUCCESS). He tells you, as his face gets paler and paler, that it is a form of Thieves' Cant but the writing is written phonetically in a strange alphabet. He translates it for you as the rest of the party searches for a potion or spell that will save him. He cannot make out the erased areas.
The "translated" slate looks like this:
Your search for a cure continues apace but to no end. You've ferreted out every nook and cranny as the poor, sickly mage/thief fights for his life.
Finally,
Maeglin gasps as the poison overtakes him. He gasps for air and says, "
This... this...," he takes a deep breath. "
This is why I don't believe in gambl-" His words drop off and his eyes glass over as he dies.
Outside the room,
Furuk sees what appears to be torchlight in the passage to the east that you just came from. It's gaining in strength -- possibly someone is coming.