1. You don't need lvl 24 to kill white pale - even lvl 12 or lower can kill it, being careful.
2. You don't need lvl 24 to kill rotworm queen - it's not immune to invis so lvl 8 can kill it easily. It's very weak anyway.
3. No one ever confirmed that General Murius drops dwarven helmet. I would rather suggest checking Horned fox, who spawns randomly in 3 places of his hideout.
Where did you get that lvl 24 requirement anyway? :D
Yeti can also be killed with lower lvl if you are cautious and heal frequently.