Although Marni had died—again, Edward frankly wasn't too worried about the Ancient Imperial Wrath Tiger Warrior.
If a group of newbie Players could reach this far even with a pack of Hyena-men on their heels, how powerful could that Boss be even if he did underestimate him?
And it was certainly true: though quick, strong and able to instakill the fully-armored Marni in an ambush, the Ancient Imperial Wrath Tiger Warrior actually wasn't killing his victims with a single blow—the System had determined that Marni was actually taken down by a series of skills that he had casted.
It was only because his sneak attack combined Rapid Ambush, Death Charge, Iron Grip, Feral Burst, and Primitive Rage along with a stack of buffs that he could tear of Marni's head, which also preserves the vanity of Marni's +7 fully-body armor.
And after knowing that, the strategy against the Boss was clear.