i've gotten the mavin thingy and i've opened
all of the chests and done everything. Now i can't seem to get out of the crypt. I can only go back as far as the two drops right after the wizard and warrior rooms. I can't even get back up to the first level. is there a secret passage in the tomb of heros that i missed. please help.

In the water area near the tombs where you talked to Nivius, you need to swim up to the underwater grates and flip a switch to open them. Once you pass through, you will be in Rasptian's(sp) area (the Rat guy) and can leave from there.

Remember the grate where you used the bobble-thing to get the crystal key for the elevator? When you pick up the Sigil of the Mavin (the ring on the corpse after taking the Oath), you're on the other side of that grate. Go there (it's on your automap at this point), pull the lever on the left wall (95% sure it's on the left), and continue out via the elevator just like you did before.

If I understand your question... this is probably the way.