There IS no party system. It's an MMO, sure, but there's no official social systems apart from friend chat/"DMs". No such thing as guilds, no party UI, no party chat, no such thing as raid groups, heck no ability to see what an entity is called let alone any details aside from what you can perceive normally*. Every entity is equal except for the fact that non-player entities cannot see system messages such as confirmation dialogue boxes. Irrespective, it's amusing how because they assume Leah to be a NPC, they just shout out their strategies in the open.
Extremely recently. She's correctly described as a newborn calamity class entity. She's just did a double rebirth from Elf to High Elf to Queen of Destruction. In fact, so recently she hasn't even looked at her new skill tree... However, she was already powerful enough with her living armour to pulp other players with her bare hands during the first large scale event. Leah is so powerful, that she has raid bosses as her subordinates.
Is Queen of Destruction an LN translation or an additional title on top of Maoh/Demon Queen/Magic Queen?
Adding on to your explanation too, it's been roughly 7 weeks since the open beta started, 4 weeks since the 1st event that drew a lot of attention to her great forest, and 10 days since her awakening as a Demon Queen.
She's been exploiting subordinate exp slavery since her 1st week and invader exp taxation since the 1st event. Production and support activities also give exp but in battle it scales with difference in strength and she's been using her far weaker NPC subordinates to continuously farm players without diminishing returns no matter how much stronger she herself gets.
Sure the players gain exp too but her effectiveness is also on another level, like how 100 exp on 100 players could increase their stats individually by 100 but Rare could increase her stats by a full 10,000 and overpower them individually or hit them all with an aoe spell. Even with a 90% debuff for example, she's still 10x stronger.
That's why the biggest damage to her right now is still her own spells but she prefers tanking known tolerable damage over being bonked by a group in a melee and risk them dealing unexpected damage or secondary effects.
The LN actually doesn't go anywhere near as intricate as this manga adaptation for this scene IMHO. I actually expected this sequence to be done in one chapter or skip ahead to the aftermath after the last chapter's cliffhanger. But instead it looks like we'll have at least one more chapter going in chronological order.
Anyhow, more opportunities to display Leah living her dreams and being a flashy boss, and it's only going to get better.
I'm impressed they showed her kicking with that long dress! twice! with heels!
the thing that aoe magic can cause damage to the caster when the spell wasn't a crit fail is kind of weird to me
Whether it was a mistake or an inability to throw, dropping a grenade on your feet sounds like a crit fail tho. With Rare's stats, her aoe spells are more powerful but with her short-sightedness, she can't aim her far enough to not include her.
Reenactment of the player's reaction:
Reenactment of Wayne's advice: