CONTAINS SPOILERS
How to Attempt the Weird/Snowgrave Route, part 4
7. This is the most important step. After killing all 4 enemies, return to the dumpster and buy the Thorn Ring. Equip the ring. 8. Initiate Berdly's fight. Noelle should have the Snowgrave spell available. You may notice that her HP will drain gradually. Don't focus on healing and instead build up the TP needed. The route requirements are now met and you can't longer backtrack at this point.
