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Oh, Rom... you are a horrible, horrible ****. And you must've been a blonde.

Tonitrus +6 works well on in-game Rom, but not as well on chalice dungeon Rom. Either way, the Tonitrus does work great on her children with its high blunt damage. For the first Rom encounter, I stay just within the circle of spiders so that she doesn't spam her raining iceberg attack, while pretty much moving the whole time to one side. I take out spiders as they get in my way, but I try to focus on getting in solid licks on Rom. When she flops onto her back for the area charge attack, roll into her to dodge it. Her final phase is ALWAYS dangerous no matter what you do, so buff your weapon and use bolt paper if you don't have Tonitrus, as every shot really has to count. In the chalice dungeon, I use a much more aggressive strategy, but basically try to do the same thing. Because there are so many things that go south with this fight, I think it almost always requires a bit of luck, especially towards the end. Just keep with it.
I was going to give you advice, but sexist slime don't deserve advice, other than "stop being a sexist slime."
Could you break Rom the vacuous’ head like the spiderlings?
If you charge R2 before she teleport away you can stop her teleport if timed.
I used bolt gem on my saw spear +9. 1rst half.
Kill ALL spiders first. Evelyn +9 and bone marrow 2nd half.
And yes hide behind pillar from attacks.. Need help?
I can try...@Crashed67
+9? I just beat Rom on the first try and I've only got a stake driver @ +6
so, the shaman bone blade works on Rom's spiderlings, but will they target Rom herself if you use the bone blade on HER?
Tonitrus or bolt paper are usually a person's first go-to for Rom, which is alright on NG, but once you acquire Bolt Blood Gems and Cursed Bolt Blood Gems, I'd suggest to start infusing them into the weapon of your choice until you have a weapon with 100% Bolt attack that doesn't require constant buffing or frequent repairs. For example, with Arcane scaling and minimal Strength, I turned Ludwig's Holy Blade into a pure Bolt weapon that does INSANE damage to Rom and her poor little babies, as with any enemy weak to Bolt (Rom, Ebrietas, Celestial Emissary, Slime Scholars, etc.). Then you can just toss the Tonitrus in the trash.
Tonitrus +7, but probably didn't need to be that high. Old Hunter's Bone. Good arcane defense gear and rune. Ignore spiderlings. Circle Rom and wait for opening amongst spiderlings. Use Old Hunter's Bone. Dash and evade, give Rom six good ones, she teleports. Watch for her attacks and stay out of their way and avoid the errant spiderling who gets close to you. Rinse and repeat. Gone in 60 seconds. Key is Old Hunter's Bone and ignoring spiderlings. I've beaten her dozens of times, quickly, using this method. Substitute quick weapon buffed with lightning paper for Tonitrus, if need be. Good luck, hunters!