Datamined changes from current PBE release. Be aware that these changes are tentative and they might be changed or even reverted prior to the live patch.
Datamining only captures numerical changes. It doesn't capture changes to mechanics and bugfixes that may also significantly affect balance.
Due to the nature of how the datamining works it may also includes some of the changes that are already added to the live version in the most recent patch.
Updated: May 15 1AM

Jax
Enter a defensive stance for 3 seconds, reducing incoming damage by 20/25/30 and gaining 400/450/500 (
) Shield. When the stance ends, strike all nearby enemies, dealing 68/104/153 (
) magic damage and Stunning them for 1/1.25/1.5 second(s).
Flat Damage Reduction: 25
[20/25/30]

Meeple Emblem
The holder gains the Meeple trait and 1 additional Mana Regen per
. The holder gains the Meeple trait and 4% Damage Amp and 50 Health per
. 
Luden's Tempest
100% of overkill damage plus 100 is dealt as magic damage to the three enemies nearest the target.
100% of overkill damage plus 100 is dealt as magic damage to the two enemies nearest to the target.

Drone Uplink

Malware Matrix
Dealing physical damage to an enemy reduces the target's Armor by 2. (Ability Damage Cooldown: 0.75 seconds)Recommended users: Master Yi and Pyke. Attack Champion: Dealing physical damage to an enemy reduces the target's Armor by 2.Magic Champion: Dealing magic damage to an enemy reduces the target's Magic Resist by 2. Recommended users: Master Yi and Pyke.Ability Damage Cooldown: 0.75 seconds. 
Sympathetic Implant
Every 5 seconds, gain 1 additional Mana Regen.Recommended users: Sona and Viktor. Every 5 seconds, gain:Magic Champions: 1 Mana Regen.Attack Champions: 15% Attack Speed.Recommended users: Sona and Viktor. 
Target-Lock Optics
The holder's first attack on each enemy deals 150 (
) additional damage.Recommended users: Pyke and Master Yi When the holder damages each enemy for the first time each combat, gain:Attack Champions: 10% Attack DamageMagic Champions: 8% Ability PowerRecommended users: Pyke and Master Yi 
Drone Uplink

Malware Matrix
Dealing physical damage to an enemy reduces the target's Armor by 2. (Ability Damage Cooldown: 0.75 seconds)At (4): If the holder is Psionic, every 3rd attack cleaves, dealing 75 (
) physical damage to nearby enemies.Recommended users: Master Yi and Pyke. Attack Champion: Dealing physical damage to an enemy reduces the target's Armor by 2.Magic Champion: Dealing magic damage to an enemy reduces the target's Magic Resist by 2. At (4): If the holder is Psionic, every 3rd attack cleaves, dealing 75 (
) physical damage to nearby enemies.Recommended users: Master Yi and Pyke.Ability Damage Cooldown: 0.75 seconds. 
Sympathetic Implant
Every 5 seconds, gain 1 additional Mana Per Second. At (4): If the holder is Psionic, their abilities deal 25% of their ability damage as true damage instead.Recommended users: Sona and Viktor. Every 5 seconds, gain:Magic Champions: 1 Mana Regen.Attack Champions: 15% Attack Speed.At (4): If the holder is Psionic, their abilities deal 25% of their ability damage as true damage instead.Recommended users: Sona and Viktor. 
Target-Lock Optics
The holder's first attack on each enemy deals 150 (
) additional damage.At (4): If the holder is Psionic, they heal 20% of their max Health whenever their target dies.Recommended users: Pyke and Master Yi When the holder damages each enemy for the first time each combat, gain:Attack Champions: 10% Attack DamageMagic Champions: 8% Ability PowerAt (4): If the holder is Psionic, they heal 20% of their max Health whenever their target dies.Recommended users: Pyke and Master Yi