There are other posts on this forum about winter care for EE that I would check out. Alocasia is not hardy in your zone, so I would dig the tuber up, wash off the dirt, let it dry in the shade for a couple of days and then put it in a bag of peat moss - paper sack, shoe box, etc.

This was the other suggestion as well for winter care. I have 3 plants ('Illustris', 'Black Magic', and Fontanesii) in pots that I am going to bring in after foliage die back, to winter over. My others, Alocasia plumbea nigra, colocasia gigantea 'Thai Giant', macrorhiza, 'Ruffles', that I will mulch heavily to get thru winter.

Susan