I can't climb the stack!

Hint 1 of 6:

You probably aren't agile enough to get up there.

Hint 2 of 6:

Have you seen anything in the Cellar or in your "Legends and Lore of Quendor"
that can increase your Dexterity?

Hint 3 of 6:

Moss of Mareilon can.  There should be a patch somewhere in the Cellar.