For the "How to Deckbuilder" achievement a lot of the guides I found online no longer match the maps they're linked to, nodes and rewards are often different making the guides unusable. So I figured I'd share what I used.

Clans: Melting Remnant & Umbra


Starting cards: Dreg & Shadesplitter


Mutators: Fallen Champion, Protect the Pyre, Permadeath

These are the basic concepts for the achievement with this setup. Hopefully they will remain relevant even if the maps get changed up.

Permadeath will purge unit cards when they die, so you don't have to hit every Vortex or spend a lot on card removal. Don't let important units die. Take all unit rewards to use as throwaway one-shot shields or bombs (Melting has some good units for this).

Skip all spell rewards and before the final fight make sure all your spells are purged.

You'll need a unit to tank and a unit to do sweep damage to kill back line problems. I used Crucible Collector and Shadoweater for those roles, on separate floors.

You'll need Morselmakers to fuel your units in the final fight.

Heaven's Gold artifact helps a lot (+1 Pyre damage per 10 gold stored).

During the final fight make sure the boss kills all your units, and make sure your units take the boss low enough for your Pyre to finish him off.

You can take the base setup and clone challenge until you find a good map. Or you can use the map I used for my step by step guide below - it's not perfect but it worked for me.

This is a brief step by step of the run I used to get the achievement. Feel free to find your own approach or a different map, I'm sure this far from perfect :)

Challenge: monstertrain://challenge/GentleTableThunder
Result: monstertrain://runresult/1315b0e9-0eab-41ae-b473-5db47881b8c2

Basics:
- Grab all unit cards, skip all others
- Take "Light of Seraph" major enhancements (+ floor capacity)
- Take all fight Trials except Ring 7
- Buff Crucible Collector HP, save other gold
- save Devourer of Death(s) for Final Fight

Ring by Ring:
1: Forever Flame (unit cost -2)
2: right, unit Crucible Collector
3: right, unit Shadoweater, fight reward Morselmaker
4: right, unit CC
5: right, copy Mm, fight keep Mm off floor 1 to avoid boss
6: left, Trinket shop (+5 health, reroll for floor 3 daze), Vortex
7: right, Hoard + Cave, fight no Trial, reward Remnant Host
8: left, purge all spells, don't shop save gold, copy RH

Final fight:
Floor 1:
- CC + Mm (they get too buff higher up)
- Use trash units to tank rough waves
- RH in front of Devourer of Death = strong combo
Floor 2:
- Shadoweater fueled by Mm
Floor 3:
- Enemies are stunned
- Any permanent units are good, especially high attack

Hopefully this is not too abbreviated, if anything is unclear let me know.

It's not the prettiest guide but hopefully it gets the job done. Thanks for reading!