Ok, so from what I'm reading it sounds like you gain slow. So when leaving the zone you are slow (unless you are also fast = normal).
The question I have is does the slow come into effect once you enter the zone. Meaning, can I not attack if I move into the zone because I gain slow?
Swamp text:
Non-Flying, non-aquatic creatures in this zone gain the slow and unmovable traits, and lose and cannot gain the elusive trait.