SPOILERS for Dungeons of Cirith Gurat!

Quest card 3 says: "When Revealed: The first player adds Uruk Chieftain to the staging area. Each player chooses a hero he controls, discards all tokens and attachments from it, and attaches it to an unattached enemy in the staging area as a captive. Then, the players make a standard series of engagement checks against each enemy in the staging area. Reduce the engagement cost of each enemy not guarding an objective to 0 during these engagement checks."

Ranger Spikes:

If an enemy is caught in Ranger Spikes, I presume they do not make an engagement check as a result of the Forced effect on the quest card...? What do you think?

When it says "unattached enemy" does that mean lacking hostages, or lacking attachments at all?

If it's the former I agree that Ranger Spikes would prevent the engagement check from happening for that enemy.

Yes I think that you don't make that engagement check since ranger spikes told you no to perform them.