OK so the way monsters work in this is you have different ranks: [spoili]
- Swarm Minions are the smallest monster, they always come in hordes and are very easy to deal with, but they can be a bother if you ignore them for too long. They often spawn during boss fights and chase after the healer to interrupt their skills. Basic attacks are enough to kill them, usually, though due to HP boosts in dungeons, several attacks may be necessary. They are very rarely taller than about 1 foot.
- Lesser Monsters come next, usually appearing in groups of 3 or 4. Boars, bandits etc would classify as Lesser Monsters. These make up the majority of the time you'll spend in a dungeon, excluding bosses.
- Elite Monsters are basically Lesser Monsters, but they come with a significant stat boost and an extra skill of some kind. They have a chance of spawning in place of a lesser monster when a group spawns.
- Minor Bosses are your Midboss things. Usually easy enough to deal with, but could take some time. You'll need to kill creatures with this rank or higher if you want a chance of obtaining Rare items.
- Elite Bosses are the end-bosses. Big, powerful beasts that could take a significant amount of time to take down. These can drop Epic rank items, and will always drop at least 3 of them, at the level of the boss.
- World Bosses are like super-Elite bosses. They don't appear in dungeons but instead appear in the Wilderness on a timer, typically once every 48 hours. To take one down efficiently, around 20 players are required. They always drop one epic item per player who contributed to the fight (people who hit it once then stand and watch won't get anything), and have a chance of dropping Legendary-class items.
- Raid Bosses are the most powerful creatures in the game, take many hours to kill, and their fights come in multiple stages. So far, no one has ever defeated a Raid Boss; even a party of the game's 42 strongest PVE players didn't manage it. They drop immeasurable amounts of loot, including the coveted Godlike items, which are unique - only one copy of each Godlike item may exist in the game.
[/spoili]
So anyway, I'm OK with her having an insta-kill chance on the first 3 types of monster, although in the interest of keeping the game fun for everyone, important mobs that everyone works together to kill won't have the insta-kill chance. How about 30% chance for Minions, 10% for Lesser Monsters, 5% for Elite monsters and 5% for Players (only in certain conditions - such as PVP arenas that involve 30 player teams and respawns where being able to insta kill won't really disrupt that much)