Warhammer: Vermintide 2

This achievement is for killing Rasknitt within 20 seconds of killing Deathrattler on Legendary difficulty. 20 seconds sounds like a lot, but it really isn't -- Rasknitt's teleporting and death animations can take up a large chunk of that time. As such, this guide should help you in obtaining this achievement within that tight time window.

For class makeup, prioritize high damage classes -- the longer the fight goes, the more likely you are to wipe due to attrition against the constant barrage of boss damage and waves of hordes. As such, our team was made up of a Zealot (great damage and surviveability -- all around best class currently in game) using the Axe & Falchion and Brace of Pistols; a Slayer (for hoard clearing and Rasknitt damage), using Dual Hammers (for hoards) and 1H axe (for Rasknitt/Deathrattler); a Shade (for huge Rasknitt backstab damage and character pickups) using Dual Daggers and the Volley Crossbow; and a Foot Knight (for horde clearing and Deathrattler machine gun resistance) using a Sword & Shield and a Repeater Handgun. Strength pots are very useful in this fight except for Shade who should probably have a Conc pot (more on that below).

The fight starts out with Rasknitt riding on Deathrattler, and during this time Rasknitt immune to damage (so save your ammo). Deathrattler himself is basically a modified Stormfiend, but with dual machine guns instead of flame throwers. His attacks include a frontal swipe attack that knocks back (blockable), a charge attack that also knocks back (also blockable), and a dual machine gun barrage (only blockable with a shield). Of these three attacks, the machine gun fire is the most dangerous, as getting caught out in the open with it raining down on you will eat up a huge portion of your health. If under fire, hide behind a pillar.

Also during the entire course of the fight (both when Rasknitt is riding Deathrattler and when he's off), waves of hordes will come over the walls and attack you. If not handled promptly, these adds can easily chip away at your health, which is very bad since this fight is long, and attrition will eventually wipe you. Therein, this fight is a balance of applying the damage to the right places at the right times.

As such, during the fight, at least one, though better yet two members of the team will prioritize killing the horde (which will take up about 75-80% of their time). In our instance, we used the Slayer and the Foot Knight -- the Slayer can use his leap ability to jump between pillars if under fire or to jump to the other team members to clear the horde off their backs, and the Foot Knight can clear the horde out in the open while using his shield to block incoming machine gun fire. With the horde handled, the Zealot and Shade worked on Deathrattler.

Like other stormfiends, Deathrattler has a controller on his back, and this is your damage priority target. Essentially, the Zealot and Shade traded agro between them while using one of the pillars to dance back and forth, keeping the pillar between them and Deathrattler and thus staying out of his melee range. While one was agroed, the other would go around back of Deathrattler and wail on the controller, doing heavy damage. Not only does this apply damage consistently to Deathrattler while minimizing melee damage, having a teammate close to Deathrattler also causes him to not use his machine gun attacks, which is a HUGE boon to the horde clearers. Note: during this time the Shade should not use her backstab ability, instead saving it for Rasknitt (see below).

Eventually, at about 80-75% health, and again at 55-50% health, Rasknitt will dismount Deathrattler for about 30 seconds, allowing you to finally do direct damage to Rasknitt. When this happens, Rasknitt must be immediately tagged and made the priority target, as he does huge amounts of damage if left alone. He has two main attacks: a short distance green lightning bolt that does a good amount of single target direct damage (unblockable), and a long distance green lightning pillar that, when hit, does significant damage over time (also unblockable), which also has the irritating habit of stopping someone from picking up downed teammates. Finally, and most perniciously, Rasknitt has a teleport that can send himself all over the arena, which he uses frequently.

So, during these dismount phases, everyone save one person (in our case the Foot Knight) should immediately pile as much damage onto Rasknitt as possible. This has three benefits -- first is that heavy damage and staggering prevents Rasknitt from firing off damage abilities and prevents teleporting; second is that you want to get as much health off of Rasknitt for the last phase of the fight; and third is that at 2/3 health (in round one) and 1/3 health (in round two) Rasknitt will immediately remount Deathrattler, which prevents the huge amount of damage that the pair can do in tandem (and speeds up the fight).

While this is happening, the fourth character should continue to clear hordes as well as possibly distract Deathrattler (either by pillar dancing or using shields to block machine gun fire).

Once Rasknitt remounts, go back to the original Deathrattler pattern. Finally, at 10% health, Rasknitt will dismount Deathrattler for the final time. DO NOT DAMAGE DEATHRATTLER ANYMORE AT THIS POINT. Your new goal is to get Rasknitt (who hopefully is about 1/3 health) to do his kneeling death animation. To achieve this, you need to get him down to about 5%-10% health. At this point, everyone should use every ability they have on Rasknitt as hordes will come fast and furious now. Once Rasknitt hits the heath threshold, he will teleport to the center of the arena, and kneel down. Once you see this, you need to finish off Deathrattler (and the Shade should consume the Conc pot to prepare for the final Rasknitt blow). The moment Deathrattler dies, the 20 second timer begins -- again, this window of time is much shorter than you think it is, so at this point everyone (including the Foot Knight) should wail on Rasknitt to get that last bit of health off (and Shade should use the final backstab). If you can do this within 20 seconds of the Deathrattler kill, the achievement will pop upon Rasknitt's death.

Remember though, you still need to finish the the level to get credit to the Empire Resurgent achievement. Sigmar help you if you're killed off by a retreating rat after all you just went through.

A few last minute tips:

-- Try to time the Rasknitt dismounts between waves of hordes. Nothing is worse than having Rasknitt drop and having a horde immediately in your face. Options here are bad -- clear the horde and have Rasknitt blast you down or get Rasknitt and have a horde chopping away at you. Neither situation is good, so proper timing can help you tremendously here.

-- Make sure to kill Deathrattler AFTER Rasknitt enters his death kneeling animation. Again, 20 seconds sounds like a lot, but it really isn't and considering that once you get Rasknitt down low enough, he teleports one last time to the center of the arena (which eats up a few seconds) and then goes into his kneeling animation (which is another few seconds), and now you have to get your team into proper position (another few seconds) -- suddenly you see your window to kill him on time is extremely, extremely tight. Save yourself this aggravation and go after Rasknitt and get the kneeling animation before polishing off Deathrattler.

-- Probably doesn't need to be said, but you need good communication and good tagging during this fight. Everyone needs to know the moment that Rasknitt dismounts and needs to be able to pick him out quickly from a crowd. Those working on Rasknitt or Deathrattler should periodically announce Rasknitt's/Deathrattler's health percentages so the horde clearers can better time things, and horde clearers need to announce when hordes are clearer or when another wave hits so the Deathrattler damage dealers can properly time Rasknitt dismounts. If you're about to drop, make sure your team knows so people plan accordingly. Communication is critical here.

-- If someone is very low on health and/or in the white health, and Rasknitt is riding Deathrattler, it might be worth it to have them die so that they can come back in a minute with half a green bar. This can prevent the team from have two or three people drop in quick succession, which will basically end your run (as its almost impossible to rez anyone if you're the last person standing due to machine gun fire and/or lightning pillar attacks).