imo --
ice hydra -- your not looking for your merc to do the killing the damage it does from one arrow will compensate for the amount of arrows she shoots.
eth fort -- if using andy/gskull you will be able to equip 4065 def eth sacred fort -- if using any other helm u will be able to use 3552 eth ap fort
helm -- i have always been a huge fan of the eth 35 str 2 sok gskull for this -- i use 24edmg/48ar/8str/8dex jewels x 2 in mine

works great for me and can wear the eth sacred fort
