The Training Dummy is a furniture you can build (the Outdoors page).
In-game description
A straw dummy on a post. Strike it to see every hit's damage, with your damage per second over the last 10 seconds over it. It never breaks, and each blow teaches a little Attack, up to 50 a day.SHOWN IN THE BUILD RING
Building it
It costs 8 
Wood, 4 Any Grass, 1 Water 2 Earth 1 Fire spirits. Take it down with DISMANTLE to get its cost back (see Building).
