You are playing Nightmare mode.

Forced: When Ent of Fangorn leaves play, remove it from the game.

"Suddenly up came fires and foul flames: the vents and shafts all over the plain began to spout and belch. Several of the Ents got scorched and blistered."
–Pippin, The Two Towers

Begin with the standard quest deck and encounter deck for The Road to Isengard scenario.

Remove the following cards, in the specified quantities, from the standard encounter deck:

3x Snaga

1x Ring-wall of Isengard

2x Open Pit

1x Machines of Isengard

3x Blast of Sorcery

Then, shuffle the encounter cards in this Nightmare Deck into the remainder of the standard The Road to Isengard encounter deck.

Finally, flip this setup card over and place it next to the quest deck. Its effect remains active throughout the game, which is now ready to begin.