Possible mastery buff/reworks

Butcher Current: Basic attacks and single target, non-periodic abilities deal 2 bonus true damage to minions and monsters. Suggested addition: AoE abilities deal 1% true damage to minions and monsters. (minimum 1 true damage per tick)

Feast Current: You restore 3 health and 1 mana on unit kill. Suggestion: You restore 3% bonus health and 1% mana on unit kill. (minimum 3 health and 1 mana)

Block Current: Reduces damage from incoming champion basic attacks by 1/2 Suggestion: Reduces damage from incoming champion basic attacks by 1%/2%

Unyielding Current: Reduces all incoming damage from champions by 2 (1 on ranged champions) Suggestion: Reduces all incoming damage from champions by 2% (1% on ranged champions)

Legendary guardian Current: Grants 1/2/3/4 armor and .5/1/1.5/2 magic resistance for each nearby enemy champion. Suggestion: Grants bonus 1%/2%/3%/4% armor and .5%/1%/1.5%/2% magic resistance for each nearby enemy champion.

Runic Blessing Current: Start the game with a 50 health shield. This shield regenerates each time you respawn. Suggestion: Start the game with a 5% health shield. This shield regenerates each time you return to the fountain.

Give tanks a little love. The butcher changes, while they could potentially aid non-tank junglers, consider how often tank junglers like could proc this damage vs fighters who would only be able to proc it once every few seconds.