Warhammer: Vermintide 2

This challenge is probably one of the easiest. You dont have to run to the end of the level. Once you entered the bell area, this is where the timer start.
you have to destroy the bell and go behind the boss in less than 75 secondes and the achievement will pop once you dropped down.

So the 75 secondes timer is only about the time you take to destroy all the chains of the bell and drop down into the opening door.
Avoiding the boss save you lot of time so just ignore him!

This achievement is both buggy in and good & bad way.

The good is that the achievement will pop with the old requirements, which is destroy the chains within 75 seconds and drop down where the rat ogre spawns from the crypt.

The bad is even though you do the requirements the achievement doesn't pop.

The requirements where changed with the cataclysm update;

The timer doesn't start until the first chain is destroy and you then need to escape through the bridge of shadows with in 85 seconds.

Hero Selection:
Handmaiden (Slayer/Battle Wizard/Foot Knight)
Ironbreaker (Zealot/Unchained)

Talents;

Handmaiden:
Spirit Echo - Asrai Alacrity - Smiter - Wraith Walk/Dance of Blades/ Willow Stance - Birch Stance - Gift of Ladrielle

Gift of Ladrielle and Wraith Walk will allow it easier to run to the exit.

Ironbreaker:
Rock-Breaker - Blood of Grimnir - Bulwark/Smiter - Gromril Curse - Dawi Defiance/The Rolling Mountain/Miner's Rhythm - Booming Taunt

Equipment;

Handmaiden:
Melee - Your Preferred (Dual Daggers has best movement speed)
Ranged weapon - Your Preferred
Necklace - Health & Blocked Cost Reduction with Barkskin
Charm - Your Preferred with Decanter/Home Brewer
Trinket - Cool down Reduction & Movement Speed

Ironbreaker:
Everything at your preferred.

Make your way through the level normal trying to get 2 speed potion & 2 concentration potion (speed equipped on Handmaiden & concentration on IB).

Once you make it to the drop down before the event wait out for a horde and clear out any roaming enemies in the event area, plan which set of chains everyone is going to go to, it's best to have handmaiden go to the right set. Have IB in front of crypt area.

Once everyone has dropped down and started to head to there chain set have IB use Career Skill to taunt enemies. When everyone is in place and ready to cut the chains do a little 3 2 1 go. Your 85 seconds start now, the bell should be destroy Handmaiden moves towards IB and waits for Rat Ogre to spawn. As soon as that happens drink speed potion and IB give concentration to handmaiden.

Once this is done everyone else let's them self be downed and leaving only handmaiden alive.

Dash through the monster and down the drop down hold block and run pass everything thing once you make it to the steps drink concentration and spam career skill all the way to the exit while holding block. (There's a potion on the steps most time if it's speed or concentration and can drink 2nd potion as soon as you see it)