There are a couple strategies listed on the wiki: https://outsiderartisan.miraheze.org/wiki/Astraea
In general, I recommend keeping her sanctioned with holy magic if you aren’t already. That alone will make your life a lot easier and is probably the most important thing you can do to keep her from killing you with fires of hatred.
Idk if u have beaten her or not but if u havnt this is what I did
:go to ranbol and farm money through prostitution
Once u have a lot of money, go to the guy that sells potions
Get the discount by sucking him off
Buy a lot and I mean a lot of health potions and health potion+ bc there's one attack does does like 90% of ur hp
Spam flash tits so lust stack prevents from attacking when needed
Once u take dmg, pop a health potion cos u will need the HP to tank the 90% dmg
(I used lightning and dark magic) Hope it rains and spam lighting abilities except energy untill there is enough stacks of bleeding since there's 1 attack in dark that deals more dmg for every bleed stack. Spam and pray u win (don't let ur hp go below 90% or you'll lose and rng for CRIT dmg
