Queen Meacidaris is protected by four linked royal guards, who must be slain first.
During the fight, Meacidaris will imprison you in a wax prison. Being in the wax prison target locks you to the prison, and you must destroy it. You can hit Meacidaris with indirect AOEs while imprisoned.
Queen Meacidaris has an ability called Slam Dance, which knocks you up and then throws you back towards the ground at maximum falling speed. If this move knocks you off her platform, the game kills you. If you land too close to the edge of her platform the game may think you've fallen even though you haven't and kill you.
Queen Meacidaris also summons "boiling honey" (small glowing yellow circles) that spawn all over her platform. Getting in these circles slows your movement speed by 75% and does 20K damage per tick. The longer the fight draws on the more circles there will be, and you can reach a point where there isn't any place to get out of the way of them if you don't have good DPS. It seems that every time Meacidaris successfully casts Slam Dance it adds a circle - consider trying to interrupt Slam Dance.