The bugs are simple. Animation timings are too fast and too slow.
The impact makes Morde 100% unusable since you effectively don't have a Q to use.
For the sake of the explanation assume his base attack speed is 1.00
I'll start with the AA
His current AA animation plays at 2x the speed it should be. This doesn't change his attack frequency but it does make his windup much faster (and therefore any AA he does will land faster and more reliably).
This is not as much of a problem unless they're going some attack speed build, in which case should you hit the 2.50 cap and have lethal tempo you hit 3.29 attack speed but the animation plays at 6.18 attack speed (but you still only hit 3.29 times per second, just a lot faster).
The Q speed is the real issue since this does negatively impact him.
He will cast Q. His first Q will hit at half the speed or full speed. It so far appears to be a total random chance that it plays the right speed. His second and third Q will be at half your current attack speed (so if 1.00 is his speed, 0.50 will be what the Q animation plays at).
This is a HUGE problem since you will have to stand and wait for the Q to land (which unbugged is an issue in itself but moving on) so unless your target happens to be stationary you will never land any Q other than the first.
Below is a video quickly thrown together
Left is on LIVE, right is on PBE. Top is AA bottom is Q.
Stats are level 1 with no items, no precision runes (so it's literally his base of 0.60 attack speed). As you can see the PBE is going by 0.30 per Q while live is accurate to his attack speed