Just beat Karst on Eradication
Took a couple of tries because the enemies kept going different directions than I expected, but using Sublimates and Diffuses early game was incredibly effective, and then spamming a billion Lustres on each chokepoint cleared out a lot of the rest. Diffuses with Surge were really good for preventing the enemy projectiles from killing my walls, while also dealing with the psychotic air units. I put them all around my base and they ALL saw use. I also threw in some Titans for fun. I didn't end up building Phase or Surge early enough to try out the Smite turret, but setting up the one carbide crucible was enough for all the Lustres I wanted.
Overall extremely fun, you need to be CONSTANTLY building or else you will run out of resources and won't be able to outscale the enemy. I have no idea how I would beat it without pausing lol. Now onto Origin, hopefully for something more relaxed because of the lack of a hard timer.