Cappa Juice

Scales with Ability Power (AP). Champions and effects flagged as AP-scaling get bigger damage, healing, or shield values when the holder stacks AP from items like Jeweled Gauntlet, Rabadon's Deathcap, and Nashor's Tooth, or from trait bonuses.

Scales with Attack Damage (AD). Champions and effects flagged as AD-scaling get bigger auto-attack and ability damage when the holder stacks AD from items like Deathblade, Infinity Edge, Giant Slayer, and Bloodthirster, or from trait bonuses.

Bonus Attack Speed makes a unit attack more often per second, which means more auto-attack damage and faster mana generation toward the next ability cast. Some carries scale beyond that — their ability itself fires more hits when they have more Attack Speed (e.g., the number of swipes in Aphelios's onslaught). Stacking AS items and traits on these units compounds: faster autos, faster casts, and bigger casts.

Effect fires when a unit secures a kill or assist. An assist counts, so a unit that only contributed damage still triggers it.

Effect fires when the unit itself is killed, commonly on items that bank value during combat (see damage-storage) and discharge it as a final payload.

A stat that ratchets up round after round instead of resetting when the fight ends. The usual trigger is a takedown — the carrier banks a stack on every kill or assist and keeps it, so early-round farming compounds into late-game power — but the trigger is not always a takedown you made. Old Growth pays out whenever any enemy dies within three hexes of it, handing your strongest Old Growth champion 30 permanent max Health each time, and Veigar banks Ability Power when the enemy it hit dies. What every source here shares is the persistence, not the kill: the stack survives the round, which is what separates it from in-combat stacking that starts again from zero every fight.