Use the acid on the dagger to obtain the Glittering Crystalline Key. Once you have the key, search for a Humming Crystal Portal, which spawns randomly in the wilderness (the portal is tiable, though not summonable, so if you chance across it before you have the acid or dagger you can save the tie.
You'll be portaled to a mountain peak in the direlands at 4.5S 81.2W. Use the key on the Strange Humming Crystal to obtain a Lyceum Recall Gem. This gem sends just the user (does not open a portal) to the Lyceum. There are also two tiable portals here that drop near the dungeon Hieromancers' Halls and can save lots of running later.
The glittering key fits neatly into the niche of the humming crystal. The hum grows louder for a moment, and the key reshapes itself before your eyes...