Power Levels allow you to, at a glance, determine how strong an opponent is, without giving you exact info on their current kit/abilities.

• They are not levels in the traditional sense. As such, there is no experience gain for killing/looting.
  
• They don't actually affect anything, they are informational only.

A Champion gets 1 "level" or "power point" for each Item and each Ability that Champion has in their possession during the match, and 1 more point for each increase in rarity past Common (Green) for those Items and Abilities.

• 2 point = Common (Green)
  
• 3 point = Rare (Blue)
  
• 4 point = Epic (Purple)
  
• 5 point = Legendary (Orange)

Your opponents will generally behave very differently depending on how your Power Levels differ from one another.

• Green (1 - 19)
  These opponents may only have a few abilities, only a few items, or they may have their full kit, but it is comprised of just Commons (Greens) with a few Rares (Blues). These opponents will tend to run from fights unless they have the appropriate abilities, or the upper hand health-wise. They tend to fight right at the start when clumped up or when nearing the Blue Power Level range.
  
  
• Blue (20 - 29)
  These opponents are more likely to have all of their abilities, a good number of Rare (Blue) Items or Abilities, likely a few Epic (Purple) ones too, and may have full Item kits. Generally you start to see opponents roam and fight more once they reach this Power Level.
  
  
• Pink/Magenta (30 - 44)
  These opponents will almost certainly have all their abilities and a decent kit to back it up. They will have quite a few Epic (Purple) Items and Abilities and probably at least one or two Legendary (Orange). You will often see these Power Levels in the final fights. Side note: I'm guessing they used Pink/Magenta to make it easier to distinguish from Blue Power Level text.
  
  
• Yellow (45+)
  These opponents are extremely dangerous.These are your typical last man standing, usually it's a snowball. A roaming aggressor may reach this stage very quickly if they are able to gank lower Power Level opponents who have found a Legendary (Orange) or two. Side note: I'm guessing they used Yellow to make it stand out more than Orange text would.