Okay, I'm going to try and explain my biome three win run for folks who were, like me yesterday, completely down after another draining but ultimately unsuccessful run.
Biome One:
Biome one bores you by now? Well, tough luck, you got to do it all the way, you got to get that snowball running somewhere. Plus, game is superfun and addictive to play so make sure it's a brand new day and you're regenerated and pumped enough, it's a hour and a half task. (+/-)
Your goals for biome one should be:
-prioritising health up purchases
-prioritising health up pickups
-prioritising finding astronaut figurine (if available at shop)
-grind if you don't have enough money, teleport back and fort, go to blue doors only and make sure you know where the skip forward to biome two and three doors are
-Do NOT go straight to biome three after getting your health to 115-120-130%, instead go to biome two after getting at least two three solid artifacts and healths/defense/profficiency ups
-Parasites are tricky, if you find a low integrity fix one, with a solid malignance like damage from fall or acid pool after enemy's death - TAKE IT, for the love of god, it might save your run (!)
Biome Two:
Alright, this is mostly chill now and you know it. Temples are all wide areas, keep your distance, explore A LOT, sidetrack A LOT (basically all of the blue doors are a must).
-Do not go for the drop down surprise rooms (!) Larger OP enemies down there can fuck up your run if you don't have a solid enough gun or your luck is down (!)
-Try to find a solid 7-8-9 profficiency gun with fast projectiles that do DAMAGE OVER TIME. Once you find that, don't ever look back. I killed Nemesis with an eight and refused to pick up 10-13 profficiency pistols and grenade launchers because they weren't as good in the long run; bigger is not always, ahem, better
-You can grind a lot before the temple here but if by temple skip portal you feel like, shit, this run is going pretty good for me right now - go even further, snowball that beautiful beastie into something even more powerful
-Don't risk malignant chest if you don't have to, go for Moderate risks, save your Ether to Copy your progress further down the level, just in case
Biome Three:
Alright, now for the final push. Basically - DON'T FUCK IT UP. It's been an hour of your hard grinding, you're starting to feel tense but you can do this, I believe in you!
Play it safe. Safe distance, smaller risks, health up, health up until at least 200% (or more, way more, always more).
-Tie Fighters are now just a minor to moderate danger, fuck em up with dmg over time from a distance, use your cooldown advantages... Basically no enemy in biome three can touch you greatly by now, you got this! If, somehow, by now you're not a beast, explore even more in three, but essentially what you got to do here is go for the tower shortcut asap, do your best there and then go for the boss.
-If you're not at full health, with astro figure and at least one health item, use teleport and GET THERE, you need those to win this (!)
-Use whatever is left of your focus and tactic to play it safely here and finally BEAT THE FUCKER
Good luck! ;)