I'm not sure how to take videos, but if you get the Dyle card buff it says: However, once you leave the swamp and go to Kerning (even with a return to town scroll), the buff ends. It seems to only work in the sewer.
1) After looking into the Dyle Card, I've noticed many other cards which have similar issues. In particular Papa Pixie card which has a buff for Cloud Park (not including Orbis' town map), so there is actually no way to make use of the buff without teleporting to Cloud Park. This has lead us to believe we are handling the buffs incorrectly, that they should not disappear when entering incompatible maps, and that they should stay visible but only provide the buff when you are in the compatible maps. Will be fixed. 2) The Mushmom Card seems intended but is slightly confusing, so I'm not sure if this should be changed or just clarified better. 3) Lots of cards do not explain their buffs properly, or not at all, but do give a buff. We will look to make sure all cards properly explain their buffs for the next patch.