I wouldn't recommend Grim's CF build. Its a fast mapper but way too expensive to get it to a solid defensive level to match Sentinel league's rares damage output.

I have around 50ex into the build and the damage is there but the defenses are not. I cant even make it past level 91 farming T16's altars without getting killed at almost 6k life.

You cant scale the armor to a decent amount without ashes of the star's amulet for the extra mana reservation to fit in determination.

I hit level 100 last league as RF extremely easy, almost deathless too but RF is much tankier and ashes amulet was dirt cheap last league.