All Brawny units gain +5 maximum HP for each kill by any of your team Brawny units throughout the game, doubled for 2 star units and quadrupled for 3 star units (+20 in Knockout). Summons count as 0.25.
All Brawny units gain +10 maximum HP for each kill by any of your team Brawny units throughout the game, doubled for 2 star units and quadrupled for 3 star units (+40 in Knockout). Summons count as 0.25.
Notes
Counts kills retroactively - kills on a Brawny unit from the round it was purchased counts towards the HP buff.
Kills add up when combining units with different kill counts.
Changed Health bonus from [15, 30] per kill to vary by star level of the Brawny unit. 1 star Brawny units get [5, 10] bonus Health per kill; 2 star units get [10, 20] bonus Health per kill; and 3 star units get [20, 40] bonus Health per kill.