The thing to know is that there are now two crucial end-game missions: King of Ashes for crowns, and Dreams and Nightmares for Radiant Fire Crystals. And really the Radiants are the bigger bottleneck.

King of Ashes is just like FSC has always been. Bring fire armor if you need it. Bring Blitz to kill Vanaduke. Bring some elemental weapon to mow down the zombies in earlier levels.

Dreams and Nightmares can be beaten with just about anything. There are very few forced fights. On earlier levels I tend to spam Brandish charges and use a gun to hit the switches. In the final fight of the final level, I tend to spam bombs. The biggest threat, in my opinion, is the projectiles from the void lichens.

The ideal loadout for you depends somewhat on how skilled, knowledgeable, laggy, etc. you are. And whether you can afford to buff your armor with status UVs. You might try reading my armor guide.