Aggression

The aggression of an infected increases as a player's threat level goes up (although not 1:1), or as the player uses more options on the strategy table (each chosen option increases aggression by 1).

The level of an infected affects their base-level aggression.

Level	Behaviors
0	Infecteds behave normally.
1	Screamers use their AOE (Area of Effect) stun skill much more often.
2	All infecteds have a larger detection range. Catapulters get a small speed boost with cooldown. Catapulters can throw up to 3 infecteds at once. Protectors uses their charge attack much more often. Trackers have a chance to dodge attacks. Normal infecteds may stun instead of slowing the player.[Confirm]
3	When Pukers puke, the skill pulls you towards them (even if the puke doesn't hit you). Catapulters can grab other infecteds from much farther away. Crawlers can jump towards a player from much farther away.
4
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6