Story Mode Requirements: Level 50...
Hard Mode: If you know what you're doing, level 49 epic mods (the ones you get from dailies) are good enough.
Nightmare: Full Columi is recommended.
I love when these guys show up in a discussion. An OP who clearly has never done EV, and is just looking for some friendly advice on gear, and someone always shows up saying 'lol lvl 40 greens is fine.'
inb4 "ur bad"
I would agree with the fellow above me. At least daily mods, if you know the fights and stuff. If you're new to raiding in general, run some hard modes and try getting a bit of Columi.