Here we go, all the way back in patch 5.22
Kill Gold
In place of traditional kill streaks, bounties turn shutdowns into global gold.
League often comes down to an optimization of 'how can I get the most value for my effort?' Sometimes this shakes out in neat ways (do we take dragon for later, or a tower for now?), but when you have to crunch numbers to tell whether or not it's valuable enough to kill a target, we may have gone too far. Bounties are a way to ensure the answer to 'Should I kill this high-profile bad guy?' is always yes, changing the question to 'how and when' rather than 'yes or no'.
Bounty tiering
BOUNTY BOARD Bounties are now visualized by a banner next to champion health bars
FAME Bounties begin accruing at 2 consecutive kills (unchanged)
INFAMY Bounties increase per additional consecutive kill, up to 5 kills (unchanged)
PERMANENT RECORD Bounties are no longer reset on death. Instead, dying now reduces bounty tier by 3.
PROBATION A bounty tier of 1 is now possible, but only if a champion dies while at bounty tier 4