This is thoroughly covered in the Character Guides section under General gameplay, and Kabal's specific DP disabling is explained in his guide:
"When you do a pop up combo with Kabal, sometimes the combo lags slightly depending on where they are when the first hit happens, and it looks as if the uppercut isn't going to come out. If your opponent releases block to capitalize the uppercut will hit. Spin them as they are falling, but do it somewhat low to the ground since you only have one hit in memory for the combo. Let them drop out and then do aaHPHP, JK air fireball, but make sure they will not be able to drop-counter. The point of doing this is because the remainder of the combo will now do full damage, and the Spin will also have done a whopping 1 pixel of damage, for a total of 45%. This also works in a much simpler scenario, after a grounded JK. When it connects, immediately do a spin when you touch the ground and spin them before the hit the ground, afterwards you can do his aaHPHP, JK, air fireball for 59%, vs 36% with the damage protection."
"Damage Protection:
This is a very necessary concept in games with single moves that do as much as 21% and no air hit-limit juggle combos. It is a safeguard that makes attacks do approximately half their normal damage (chip damage is generally 25% normal damage). Grounded Jump Kicks activate damage protection, so anything you connect after a JK will do half damage. Certain special moves activate damage protection, like Male Ninja Teleport Punches, Stryker's Riot Gun, Mileena's Roll, etc, while others do not, like Robot Ninja Teleport Uppercuts, Harpoons, and Shang Tsung's Ground Eruption. Cyrax's and Sheeva's Throws can be juggled off of, and they both activate damage protection. In MK3 they did not, and you could score reasonable damage off them. This was a pointless change, as they are now even more crippled than before. Stryker and Sonya's command throws (the Baton Dash and the Leg Grab) have their own damage protection built in, in which the move itself is reduced to half damage after 3 hits combo before it, and if you get them in an autocombo, they will do 1/4 their normal damage if the combo goes beyond 3 hits. Kabal's spin is the only attack that can turn off damage protection. If you do his pop up combo, and only the uppercut connects, spin them and let them fall to the ground. On the way to the ground do aaHPHP, JK, air fireball, and you will get the full damage for the juggle, plus 1% for the uppercut in his combo, and 1 pixel from the spin, totalling 45%.
Example character: Human Smoke
Block a teleport punch from Another Human Smoke,and he goes into punishment mode. If you are mid screen, do aaHPHP, JK, teleport punch, harpoon, 3 hit pop up, aaHP, JK, air throw. The result is (with the air throw counting as a hit and adding damage) 11 hits 68%. To break this down completely and understand where the DP comes into play: aaHPHP = 13.6%, JK = 15.6%, teleport punch = 9.5% (activates DP), and now your harpoon does 2.5% intead of 5%, and the 3 hit pop up do 9% instead of 19%, (the remainder of the hits do what they should do after his pop up).
Your new combo is aaHPHP(13.2%), teleport punch (miss)(0%), aaHP (6.6% and replacing the teleport punch which does 3% more), JK (15.5%) harpoon(5%), 3 hit pop up(19%), aaHP, JK, air throw. 11 hits 78%. Even if you do aaHPHP, TP miss, aaHPHP harpoon, the combo will do 1% more than the other.
This is not always a usable combo because it depends on how close to the edge of the screen Human Smoke is, but it shows that the same amount of hits, with one hit doing less damage than the DP activating alternate move, will result in more damage.
Example character: Sonya
aaHP, JK, leg grab 3 hits 43% (no DP)
JK(DP), aaHP, leg grab 3 hits 29%
aaHPHP, JK, (personal DP)leg grab, 4 hits 33%
Example Character Ermac:
JK, TKS, aaHPHP, JK, TKS, aaHPHP, aaHP, JK 8 hits 52% (counting the slams' damage)
aaJK (meaning while both players are in the air) TKS, aaHPHP, JK, TKS, aaHPHP, aaHP, JK 8 hits 91% (again counting the slams damage) - identical combos, huge damage difference because the JK hit in the air."
