That card reads: "Cave Eel cannot be engaged unless the active location is Underwater ."
The encounter phase has two parts. The first where the players optionally can engage enemys and the later where engagement checks are made. But from the wording in the rule book I'd say both are "engagements". So, that eel with its cost of 20 cannot be engaged (under any circumstances) unless your location is underwater?! (Even with e.g. tactics Aragorn.) Anyhow, the wording on the card itself sounds "pretty active" - so no optional engagements, but "passive like engagements" in the latter part of the engagement phase will still force the engagement?? Which one is it?
Help please!