The Boss Trophy is a wall hanging you can build (the Decor page).
In-game description
The head of a lair boss you've beaten, mounted on a round slab of log. Choose which on this page. E reads when you first beat it, your fastest fight and the hardest lair.SHOWN IN THE BUILD RING
Building it
It costs 4 
Wood, 1 
Oathfire Tusk, 1 Earth 1 Fire spirits. Take it down with DISMANTLE to get its cost back (see Building).
