about nova drop

wanna know how to increase nova drop like every 100~200 1 nova
since it's rarity = 2
even when i make _RefDropClassSel_RareEquip = 1 no drops
9999999 no drops
dont tell rarity = 3 it will rain nova's :D
even when _RefDropClassSel_RareEquip = 0 since rarity 3 for normal items etc