Hit Levels
There are five hit levels in MKX, as defined by Infl's Fighting Game Glossary they are:
Unblockable
Attacks that cannot be Blocked under any circumstance. The most common type of Unblockable Attacks are Throws, but there are also some Strikes and Projectiles with this property. In this wiki, "Unblockable" will be shortened to "UNB" to prevent wikitables from becoming too big to view normally (see the notice at the Front Page's "Introduction" section)
Overhead
An attack that must be blocked while standing, mostly used in Overhead-Low Mixups, if you try blocking an Overhead Attack while crouching you will be hit. In this wiki, "Overhead" will be shortened to "OVH" to prevent wikitables from becoming too big to view normally (see the notice at the Front Page's "Introduction" section)
High
An attack that will whiff (miss) on a crouching opponent. However, High Attacks will still connect with opponents who are crouch blocking (D+BL)
Mid
An attack that can be blocked both standing and crouching, most of the roster's attacks will be either Mid or High
Low
An attack that must be blocked crouching, mostly used in the aformentioned Overhead-Low Mixups to find an opening on your opponent's defense and start running your gameplan, if you try blocking a Low Attack while standing you will get hit
Chip Damage
All attack's in MKX will cause chip damage while blocking, both from normal moves and special moves alike. Throw teching will also cause 2% of chip damage as well.
X-Ray Meter Gain
You only gain meter when you attack blocking opponents and perform Special Attacks. This means proactive players inherently also get more damage and escape options, so don't be too passive!
Damage Scaling
Damage Scaling is a system that reduces the damage for each hit in a combo as it goes on, in MKXL this makes it so that only the first hit in a combo does 100% of it's damage
The second hit in a combo will always do 95% of it's damage if the first hit is grounded, and 90% of it's damage if it's airborne. But how the combo scales after the second hit depends on the type of attack the second hit is
If it's a 1/2 Attack, it will scale to 90-85% (-5%), if it's a 3 Attack it will scale ~85-80% (-10%), and if it's a 4 attack ~60-55% (-30%). There are exemptions to these examples, but they're uncommon, multi-hit attacks such as a barrage or a grab can sometimes scale their own hits, but other times they don't
Launchers tend to scale damage a little more than other hits, but it's not a very noticeable difference (~5-10% more scaling)
The damage scaling done in a combo will also apply to any OTG attacks that you do after it, X-Rays also suffer from pretty harsh scaling, so if you're planning to use them in/after a combo, make sure to keep it short so the scaling doesn't affect them much
Juggle Scaling
Juggle Scaling, also known as Float/Gravity Scaling, is a mechanic that makes an opponent fall down to the ground faster and faster as a Juggle goes on to the point where the opponent falls down faster than you can attack them.
Every attack done to an airborne opponent contributes to Juggle Scaling to different degrees, Restanding an airborne opponent will not negatae Juggle Scaling