>>3786199 (OP)It's not a boss fight, but probably finding Pariah for the first time in Fallout 2.
>Find dog on a random encounter.>You'd think he's Dogmeat.>But he is surrounded by a bunch of dead bodies.>Makes his way into your party, leaving you out of one companion slot.>Brings your Luck to 1.>Jinxed perk were you have more critical failures.>Can't be dismissed.>Has a huge HP pool but runs and hides during combat instead of fighting or soaking up damage.He can ruin your run if you are not prepared, especially in the early game.
I still like that dog, especially after one evasive, Unarmed run I did some years ago.