I can agree with you here. In my opinion, Mrs. Slitherss deserves to be more of a threat to the player. As of 0.1.8, you can take her out in one shot with any hand-to-hand weapon if you zoom in fast enough while she's monologuing, or just play keepaway and spam pineapple projectiles at her, and expect to live through it..
Granted I'm all for difficult bosses being possible to defeat easily as a reward for skillful use of a given game's mechanics; however, Mrs. Slitherss is so easy it hardly feels satisfying.
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Pertinent to the topic I have to admit; The ease with which Mrs. Slitherss' can be defeated is much ado with why I dislike the Draginslayer so much. Making Mrs. Slitherss prospectively a true force to be reckoned that can even keep maxed-out and skillful players on their toes would at least make the OP slab of metal feel slightly less undeserved.