Why does the Free Ranger help us during the Nightmare Duck of Death instance? I understand why he helps during the main storyline, but it seems out of place to be in this fight, as well.

Clearly, this isn't a huge issue, but any future Nightmare boss additions shouldn't be exact carbon copies of their main storyline mechanics. Old Scratch and Brass were more enjoyable due to new battle mechanics (although Brass's mechanic is just new to him).

the minutemen on Sep 21, 2018 wrote:

i agree. the Free Ranger is also pretty weak. i mean if we could get loot unique to him along with Duck then i can understand. but i dont believe Free Ranger has any unique loot.

He's an ally, so he doesn't drop loot, now, if they made a second task of: "protect the Free Ranger", then there would be a reason to have him there.
As it is, he's at least something the DoD & minions can attack besides your crew.