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: Mar 15 3PM

Dragonguards
When Jarvan casts, Shyvana gains 100% of the Shield. When Shyvana casts, Jarvan jumps in and deals 100/120/140/175% of his Armor and Magic Resist as magic damage in a 2-hex radius.
When Jarvan casts, Shyvana gains 75% of the Shield. When Shyvana casts, Jarvan jumps in and deals 100/100/125/150% of his Armor and Magic Resist as magic damage in a 2-hex radius.

Ascension
After 12 seconds of combat, gain 40% Damage Amp.
After 12 seconds of combat, gain 35% Damage Amp.

Aura Farming
Gain a 2-star 5-cost champion holding a recommended item. You cannot field it until Stage 4-2.
Gain a 2-star 5-cost champion holding a recommended item. You cannot field it until Stage 4-3.

Bringer of Ruin
Every takedown Atakhan scores permanently grants him 1% Ability Power and 40 max Health. Gain a Briar and a Sion. (Current Takedowns: 0) Every takedown Atakhan scores permanently grants him 1% Ability Power and 30 max Health. Gain a Briar and a Sion. (Current Takedowns: 0) 
Component Heist
After 4 player combats, gain 1 of every item component. Gain a random component now.0 0 After 5 player combats, gain 1 of every item component. Gain a random component now.0 0 
Malicious Monetization
Gain 10 gold. For the next 2 rounds, enemy champions drop 2 gold when killed.0 Gain 7 gold. For the next 2 rounds, enemy champions drop 2 gold when killed.0