I'm imagining this on Biotics Lab...
You hear its footsteps, thud, thud, thud, and no screen shaking for gameplay reasons, and you turn to the double stairs on your right, and the entire hallway is blocked by a dark shape. It's the Behemoth! You open fire with your M14 and empty your mag with bodyshots... but alas; It's unscathed!
You throw your grenades and reload your M14, and backpedal into some clots and gorefasts. You're dead.
Your teammates see the death message, and prepare for hell. Following the Firebug on the team that prepared for this situation in advance, you see him empty his Mac-10 into the head region of the Behemoth, lighting it on fire. You call hacks because your M14 can't do that; your teammates laugh at you and insult your intelligence.
The Firebug switched to his Flamethrower while simultaneously berating your stupidity and clears the hall behind the Behemoth with his flames of death. The Berserker moves in and starts chopping away with the Fireaxe that he packed for this occasion, and the Commando reports it's super effective; with 1/30th of its frontal health going down per alt-fire. He's dancing back and forth to avoid the melee attack, with the Firebug keeping the hallway behind it clear.
It's now moved past the spawn point and the Berserker stops attacking and the Commando takes over, to make it retarget onto him. The Support and Berserker are now assaulting its back and causing it immense damage. The Sharpshooter is dispatching the Scrakes, Husks, Sirens and Fleshpounds with ease while the Medic does the same with Bloats and calls out new targets.
The Firebug is keeping the main specimens dead and the area safe for everyone; the Behemoth is dead, and you call hacks; your M14 couldn't own it, how could they? And now you're enraged that you're not number one, and you vow to get your teammates killed so you can have the most kills.
Yeah i threw in a stereotype for the lols.