This achievement popped for me after I had beaten the 7th arena and had walked out to the shop. The final wave is to fight one of those 'Stalker' lizards that you would have fought previously as a boss type with a hp bar. This fight is a bunch of bugs to fight in waves so switch up to grub resistance armour. There is 1 final fight that only becomes available after you've beaten the game so don't panic that the achievement didn't pop after those first 6. Each one took me multiple attempts to beat but there's no harm as you'll respawn right outside to have another try anyway. These fights can be a bit tough, especially some of the later ones, but as long as you use the armour I mentioned and use your strongest weapons you're comfortable with, you'll be able to overcome them.

*** Spoiler - click to reveal *** gasmaskįrom the shop here to progress the story. They become available not too long after once you are told to return to this area, and you'll need to do these to earn coin to buy the The next 3 fights won't become available right away I believe. You'll first have 3 fights available and pretty much need to do these as you need more coin to buy the cake from the shop to progress. I'd 100% recommend buying this as it gives you max resistance against the enemy type in the arena I believe on the right in there is also a guy that sells an armour piece for 20 monster parts, if he's not in that room it's in one of the other two rooms on this floor. There is a bench, bug juice station and poison barrel in the door next to the shop to heal for each fight. There is a shop here to buy arrows if you need to restock for the first 3 fights, but once you've bought the cake and used it to open up the next sector there is an arrow restock barrel down there when you head right so may just be worth running to restock if you don't want to spend so much. On the left-hand side once you go up a floor. *** Spoiler - click to reveal *** Moletown

Tails of iron achievement guide