He's a black bison with red eyes, gold horns and small grey legs - each of which move backwards and forwards at the knee. The back legs move back at the hip as part of the TF. The bison mode has a gimmick - pull the tail back and the top of the toy - from head to back - rises up and fires a missile.
TF: Bend the back legs back at the hip to form the robot legs, fold the beast feet up into the legs which will probably in the process save you the trouble of folding the robot feet down as they'll fold out as part of this movement. Unclip the sides of the beast and fold out & forwards - each is attached to the main body by a connecting strut. Turn the robot waist round 180 degrees. Fold the front beast feet up and in. Fold the panels beneath the beast mouth up & forward then swing the robot arms out behind them. Fold the arms out to the sides. Fold the front beast legs down to form the sides of the chest, and then the beast head forward to form the robot chest. Finally bring the robot head up - along with all the missile launching gimmicky - to sit on & behind the robot's shoulders. There's a clip under the missile launcher that should lock this in place. If it's loose you've not got the clip in the right place.
Balance for the robot can be a little dodgy, but folding the beast legs down from the back of the robot legs to act as heel spurs helps a lot. More grey is exposed on the robot's upper limbs, with the lower limbs, waist and face being white. Like several BW toys of this time there's a launcher embedded in the face/mouth - here it's the missile mentioned above which is once again activated by pulling back on the tail. His articulation includes bending ankles & knees, ball jointed hips, a waist joint, shoulders that lift up at the body (part of the TF) and have a ball joint at the arm and elbows that bend up & also have a ball joint allowing the lower arm to turn and bend in.
Not a bad BW toy, but it's totally built round the gimmick which leads to a large amount of bison fur and tail sticking out the back of the head in robot mode !
Big Horn is a relatively minor repaint - in beast mode he looks virtually the same ! It's only when you get to robot mode you see that he white is now red.
From my perspective the western version - Bonecrusher - looks the better of the two.