Swapping off of the covenant isn’t really an option because you’d have to change a large portion of your build without life leech. You do need probably 800-1000 more life to make comets rain more. Overwhelming offense = the best defense.
I’d probably get a heart of the well diamond that has 10%+ of leech is instant to also help with the faster comet rain. I haven’t tried the ele weakness version of CoC comet or any version of it on Oracle (i played entangle on Oracle), but spark might help since is has a pretty large AoE. My comets on blood mage typically kill monsters before they’re anywhere near close enough to attack me.
The single most important thing to do if you’re dying often in maps is to filter out the overly dangerous waystone mods. Since i started doing that a couple of months ago, i haven’t died a single time in maps. Filter out things like reduced max res, monsters penetrate resistance, monsters fire additional projectiles and don’t run maps that have % increased monster damage plus multiple gain as extra damage mods on them. You should also be aware of which waystones you’re running in the cleansed maps that have increased effect of prefix mods. only run waystones in those that don’t have multiple damage add prefixes and you can ideally run corrupted waystones that don’t have any prefix mods at all.
The regex i use to filter my waystones is “!% ma|tes|oj|chi” (“! = “not” lower max res|monsters penetrate res|multiple projectiles|chilled ground” because i hate chilled ground). Not sure if you’re familiar with how regex works, but if you type anything in quotations it will look for that exact combination of letters/symbols on items and the | symbol separates the different things to search for. You might want to add |ign at the end to also avoid ignited ground since your effective HP is pretty low. If you type that into your stash filter box, the waystones that are highlighted are good and the ones that are grayed out are bad and should be sold. Use poe2.re if you want to customize the regex to other mods you want to avoid.