Exactly how are Avenger elites buffed when one of them dies?

Question

I understand that elites with the Avenger property get stronger as the others in the pack with that property die, but how exactly do they get stronger?

I'm looking for hard numbers.

Answer 1

Only Champion monster types will spawn with the Avenger trait. If a Champion touting this ability appears, it can imbue all other Champions in the area with the same type of powers it spawned with, increasing movement and attack speed and damage inflicted until the foe is felled. This effect may be stacked up to three times.

Source

I highlighted the important bits.