Emissary

This trait is active only when you have exactly 1 or 4 unique Emissaries.

(1) Gain that Emissary's bonus
(4) Gain all bonuses. Emissaries gain 200  and 20% 

Ambessa: Allies gain 2 Armor and Magic Resist for each opponent defeated. (@TFTUnitProperty.trait:TFT13_Ambassador_PlayersDefeated@/7)

Garen: On Combat Start, Garen and allies to his left and right gain 20% of his max Health.

Nami: Allies' attacks grant 2 bonus Mana.

Tristana: Allies gain 6% Attack Speed per star level.