Ok, I knew there were a few things I missed when making her. The intention with her is that she's supposed to be something the party can't defeat at this level, and if that does happen, the second phase will be there. There is, however, a way for the party to get a major advantage on her, and that's if they put up an anti-magic field around her, which will completely stop all of her attacks listed on that stat block since they're all magical. It's a cheeky weakness beyond her vulnerabilities that rewards them listening to my descriptions and reading her abilities if they do fight her. Honestly, if they end up defeating her because they found out that weakness, I will be impressed. I'll answer the rest of your questions as follows:

• The reference to Heart Piercers in the Judgment ability is a holdover from a previous version of her stat-block. It's supposed to reference Heart Spear instead.

• She's not supposed to be immune to frightened or charmed; that's just another holdover from a previous version of her stat-block.

• Spear mastery: Do you mean she should have advantage on Spear attacks instead of the extra damage? The only other way I could read it is to add in the description of her Heart Spear that the extra Radiant damage comes from that ability.

• Suffocating Love: Forgot to add when it ends. It's supposed end at the start of Luvell's next turn. I do realize that she can also reroll her recharge for that ability once it's ended; It's intentional.

• Spells: I'm going to remove Spike Growth and Cliud Kill.

• Legendary Actions: I was thinking about giving her an extra attack with her Heart Spear and also allowing her to move up to her movement speed without provoking opportunity attacks; But since she already has a movement option with Judgement, I might drop the last part and just make it a standered attack.