Strategy for the final boss

[Murtor]

Hey, I'm new to the game and managed to make it to the final boss on my 5th run. Had a good time with Mira, Stray and Anomy. Don't want to say I breezed through the run. But it was alright. Untill I had to face the boss in the library.

First phase was clear: Get rid of these clones. Second phase was alright, even though I didn't manage to completely understand all the mechanics (which was probably the reason why I couldn't defeat the boss).

What caught me off guard was that the boss had a third phase with its core breaking apart, revealing another 500 (?) HP. The battlefield was filled with crytals at this point and I had no idea what they actually do and how to handle the wide aoe attacks on the field.

Before I start another long run (and probably fail), I'd like to hear about other people's experience how to handle the boss. What need I be aware of?

[KingOfCharge]

You can inspect everything the boss is about to do to learn what it does.
What those seemingly absurdly strong aoe attacks do is get weaker close to the edges, when you’re next to a space not getting hit you might as well not be getting hit

[Murtor]

Made it in my next try, thanks!

I unlocked Verica with my last (failed) try and gave it a shot. As a supporting character she was pretty damn helpful. How the AoE effects work at the final boss also helped a lot. Same as when the boss spawns his minions or receives healing. For quite some time I let one of these shadow minions roam around freely. If I have understood correctly, the boss will not pop out more of his minions, as long as there's at least one around. Also, at the very start of the fight, I bought some time (action points/healing) by leaving that one minion alive, avoiding the 2nd phase of the fight.

Not I gonna check out the last two characters I just unlocked and look for the true ending.

[KingOfCharge]

You are correct on how the boss summon works