REFUGEVILLE

Well if there's one thing more vulnerable than a giant with feet of clays it's one with feets of meat. Talk about an apparent Achiles heel. ...Something something pun about being afoot....

Anyway seriously:
-Snare the legs with the chains and cut the tendons with the hooks and make that thing fall on it's knees (literlay).
-Totango and a couple of the most agile warriors to crush the ghoul skulls as they fall (or better sever their necks).
-Have half the archers concentrate on the Box arms and legs to make sure the box can't swipe our people away (or at least with the constant stinging ot'll be in too much pain to aim correctly) while the rest help finish the ghouls

Once the box is paralysed, we can have archers easily shoot some flamming arrows in that mouth and then Totango can get in for the clean up.

Aternative strategy:
The journey between both villages was only three hours which means the distances are quite short. So:

-Use the sigil of bravery to make the Box hunt Totango and lead it near the giant hole.
-Then shoot the thing and hack in the back of his legs to make it fall in the big hole.