My intuition is "No. It's still immune" because at the end of the day it's a card effect. However there is this quote that makes it fairly ambiguous to the point where I'm leaning toward that it is not immune.
From Caleb: " However, the ranged and sentinel keywords do not target the enemy, rather they affect the character they appear on and allow it to take advantage of framework actions that no enemy is immune to. "
Coney in a Trap doesn't explicitly 'choose' the enemy and it seems to operate more at the 'framework' level rather than the 'target' level. Essentially, the card itself is not affecting the immune enemy specifically, but rather, buffing me the player, stating, I am unable to be attacked by the next thing that I engage. I'm allowed to engage enemies, I'm allowed to play this card, and rather than directly stating this specific enemy, at the framework level, I'm no longer allowed to be attacked because it modifies the rules of the game, not the enemy itself. It's a stretch, but I really think this is the case.
I'm allowed to engage 'immune' enemies, thus prompting this card's 'Response:' allowing me to play it. It doesn't 'choose' the enemy itself at any point. Just references the enemy. The ruling on Quick Strike (and Hands Upon the Bow) is that it works against 'immune' enemies because it functions at the 'framework' level. This feels very, very similar. If I'm allowed an out of phase attack by modifying the rules, wouldn't I then be allowed to deny an attack by modifying the rules?
Cards and quotes below---
Coney in a Trap
Play only if you control a unique character with the Ranger trait and another unique character with the Warrior trait.
Response: After you engage an enemy, that enemy cannot attack you until the end of the round.
The Mûmakil #9. Lore.
Quick Strike
Action: Exhaust a character you control to immediately declare it as an attacker (and resolve its attack) against any eligible enemy target.
Core Set #35.
Tactics.
Hands Upon the Bow
Action: Exhaust a character you control with ranged to immediately declare it as an attacker (and resolve its attack) against an enemy in the staging area. It gets +1 during this attack.
Haldir, The Fellowship of the Ring
Shadow and Flame #131. Tactics.
"Hi Thaddeus,
And for the "Framework" Explanation
Hi Jan,
You cannot attack an enemy that is immune to player card effects in the staging area because the game does not afford players those kind of attacks as a normal framework action. Therefore any player card ability that allows you to attack an enemy in the staging area, such as Haldir or Hands Upon the Bow, would not work on Host of Angmar because it would be immune to those effects.
However, the ranged and sentinel keywords do not target the enemy, rather they affect the character they appear on and allow it to take advantage of framework actions that no enemy is immune to. So you can use sentinel to defend the Host of Angmar while it is engaged with another player, and you can use ranged to attack it.
The Host can be tackled a couple of different ways: 1. You can dog-pile it with a lot of characters, including your friend’s ranged characters, combining their total attack. Cards like For Gondor! can help with this strategy by giving each attacking character +1 ATK. Or, 2. You can build up several super high attack strength heroes with lots of attachments that grant attack bonuses, such as Gondorian Fire and The Black Arrow. Since the Host’s engagement cost is 50, an event like Unseen Strike can help in a pinch.
I would say that having several characters with the ranged keyword is very important in a multiplayer game so you can pile on the attack strength regardless of who the Host is engaged with.
Cheers,
Caleb