for what rate is mavka?
I am not sure if i understand your question. Mavka is a plant type monster in Moscovia Dungeon, 3rd floor, with about 5k HP (depends if the server is pre-re or renewal). You can most likely 1-2shot it with DS with fire arrows, you don't need any special gear if you kill it from average distance, on 4x drop rate settings it drops for like 60% Crystal Mirror (NPC sell with OC 10.000zen) and 12% Witherless Rose (NPC sell with OC 27.000zen) and 90% Blue Herbs(Sell to alchemists 1k or make Blue Potions by yourself).
You can also use a meele Rogue/Assassin class using Steal, which is quite handy (with assassin i make around 10m/2hours without @autoloot on 4x drop) but you have to count on that you will have to use some potions when you get hit by some surrounding monsters using magic.