There is some nice motion in here for sure. There is some problem with weight when the dragon brings his leg up. Screen's right leg is completely straight and not moving throughout. Dragon's whole body should move to the screen right at the same time as he moves up so weightless on the other leg to bring it up, it's nice to see overlap between body and leg coming down, but I wouldn't bring the body lower before planting the leg. Make foot straight down for contact and then bend the ankle. I would try to work a bit on that first pose, the legs are so far apart from each other, leaving a big gap, I would try to move a bit around those legs to create a nicer pose.
For the jump, it's nice to see opening the wings and bringing them down to get impulse but I would delay the body coming up after the wings are completely down like the wing that you got from flapping the wings so hard is what makes the dragon be able to get airborne. Also, remember to avoid everything being so perfectly mirrored. change a bit the pose between the left side of the body and the right side.
When on the air, you are losing an opportunity to flap your wings before moving into attack. Again I would wait for a wing flap to move the body forward as an impulse.
Not really sure what motivates the fall, if it's either an injury, maybe a gust of air?
The tail should come down once he hits the ground and body should move further forward as right now the legs are stuck in one place and body overshoots and comes back like he was caught with a rope or something like that.
The last thing is when he gets up seems like the body hits a wall, should be a bit more follow thru overall