So I just finished a re-read and this one's brutal. In 'End Arcanimus', the final confrontation with the God-Phantom is basically a magical meat grinder. Lyra the Spellslinger makes it, but she loses an arm and her primary attunement, which is a huge deal because her identity was so tied to that power. The scholar Fenrir also survives, but he's catatonic for the last chapter after channeling the True Names; the epilogue suggests he's recovering slowly, but his mind is kind of shattered.
Kael, the shield-mage, doesn't make it. He sacrifices himself to contain the backlash, and it's a proper heroic death, holding the line so the others can seal the rift. It hurts because his and Lyra's simmering romance just gets cut off. The ambiguous one is the rogue mage Varien. The text describes him being consumed by the collapsing void, but then there's that last line about a 'shadow with a familiar smirk' seen in the market a year later. The author loves leaving that door slightly ajar.
Overall, it's a survival rate that feels earned, not generous. You're left feeling the cost more than the victory, which fits the novel's whole theme about the price of power.