My first rb build: Lunia Skill Calculator(JP)
I had more points to work with (sp+1 pre-rb, sp+1 post rb, waltonian post-rb) and completed it at 74, but meh.
-Screw mp regen, guild mp pots for life, yo.
-Hp regen is nice, but I would put that on the backburner for more smash. If you go for 80, I'd start pumping that as the next thing as per what Griever said.
-Burning land cannot be canceled by myth mobs after an iron bomb+dash cancel, great for more damage while you're waiting for impartial to cooldown, but obviously you would not use it on bosses for safety concerns.
-Maxed normal amp makes more and more of a difference as you get up there in str. At 4k you'd be losing about 600-700 damage per hit if you did not max it.
-Shotgun is there for b3 soloing, you can remove it if you want.
-Sulfur rain is a tertiary attack for when I get into a boss' hitbox, after the two impartials. You can remove it if you want.
-Magma is for maneuvering purposes, I guess if you really lack hotkey space/not used to it you can remove it.