An assist is the action of helping an allied champion kill someone. You can either score an assist by hitting (without killing) the champion in the last 10 seconds before their death, or by contributing passively during this period of time.

When a champion is killed, the killer gets a certain amount of Gold, while a reduced amount is shared between all the champions that assisted the kill. See bounty for additional info.

Killing an enemy champion within Death from Below grants the last assisting ally full kill gold.

Secondary System

Champions also gain assists on kills if they:

Applied any type of crowd control, except Blind Reveal attack speed slow

Debuffed an enemy, even if that enemy was immune to the damage.

Supporting a champion that contributed to the kill (e.g. healing, shielding or buffing an allied champion).

Ashe's Hawkshot

Champions will not gain assists if they:

Triggering effects with assists

Champion abilities, items and runes that trigger an effect with an assist can be seen on the takedown page.