The claw attack looks fantastic. Nice squash and stretch and anticipation of the movement. I particularly like the messy, splashy debris during the swing, and how the head wobbles and deforms during it.
Consider incorporating some more of that wobble and splash into the spinning attack, and adding some wider splatter to the brain-busting death animation.
You could also animate the bottom (torso, claws, face) during the death more; currently that area hits a point where it more or less freezes while it waits for the head to finish bursting. Consider making the eyes pop even more (or, conversely, make them close or turn to X's). The limbs could move outwards from the body to suggest limpness, while the torso could tilt and sag a bit more continuously.