TL;DR - I was already a fan of Karax. As I suspected from reading his updates that it’d be an overall buff and that wouldn’t get me to use him any less. That’s been my case from finally getting to try him out since the update. He’s not the best to play, but he’s sure a lot of fun!
I use at least 4 of the upgrades that got discounted by 50/50 (OS stun effect, Solar Lance setting fire to ground, towers +2 range, and towers +25% attack rate), so that much is nice. The other 4, I use Shadow Cannon a lot (for Immortal), and Reclamation (for Energizer) as needed (it’d be nice if this had more range). I still don’t really use Mirages (Phasing Armor) and Colossi (Fire Beam). For the latter, my allies already had AoE covered, so I skipped it for those cases.
Losing the unit discount mastery for the buff to hp and shields was a bit of a shame, but like any CO with their own weaknesses, you adapt and move on. Their extra tankiness doesn’t make them invincible, but they do indeed live longer, which does save you resources in the long run (which also indirectly goes towards DPS), and frees up APM to do other things. I’m currently at a 15/15 split for that new power set mastery. His top tiered units are hella expensive, but TBH, I wasn’t making many of them even with full points into the former unit cost mastery.
Karax can’t just mass up Goons or their equivalent and A-move to victory, so you rely on SoA lasers to deal with air and other tougher situations, and use map knowledge to set up towers in areas where you can draw attack waves to (not to mention reinforce Warp Gate units, and restore shields with Batteries). Purifier Beam on much lower cd means I can actually use it for many pushes into fortified areas.
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I’m skeptical that this will draw in those who were Karax naysayers. However, I have gotten quite a few Karax partners so at the very least, people are intrigued. One player managed to get Carriers up and running quite quickly by rushing to them, while still doing a bit for defenses. Another Karax partner was when I played as Stukov, so I finally got to see how Chrono Field effects him (the charges from the Infested CC are noticeable and welcome!)