So I just watched a few video guides of Hard Mode for the raid and just want to confirm with all you guys that the strategies presented are still viable or the best ones:
Confluxes: Yes, spirit bloom room is safest, but you have to be careful when going for it, especially people on the right side. As soon as enemies/confluxes despawn, make a break for it. This will happen before the text about "Templar summons his legions"
Oracles: Only 1 person should jump down to start it. All 7 oracle spawns can easily be shot from the elevated platform right behind the spawn point. The front left oracle can be shot from the far right side. It is possible to jump back up but doesn't really matter, this phase can be easily handled by 4 people even on hard, so 5 is plenty.
GK: Personally I hate this strat and only view it as a substitute for insufficient DPS. Max your weapons people! Do left portal first, 1 person goes behind minotaur spawn at the top and covers that, 3 people cover right portal, 1st relic guy and somebody w/ Gjallahorn go in right portal. Relic super + Gjal to kill right GK, grab relic and get out. Everyone collapses to the middle and defend the conflux, mainly the pretorians spawning from the left and right portals.
Atheon: This is a pretty good, safe strat. Certainly not the most efficient but is plenty as long as people have maxed Icebreakers, etc. Even safer is to go to the back of the room instead of the middle platform where people can fall.
I just got my 50 raid clear grimoire card, so I'd be happy to help you run a hard raid if you are on PS4. There are a lot of details that are hard to cover in a post, haha.