I wanna make an Eldrazi deck what expansion should i buy packs from?

[Prof. Cabbage]

i dont know what color yet i justknow i wanna have a bunch of eldrazi

[Vincent Valentine]

don't ♥♥♥♥♥♥♥ do it

[Rosenkreuz Kontrol]

G/U Eldrazi Emerge deck is where it's at... just burn through Eldritch Moon and you'll be fine.

[Valance]

I think if you want the strongest cards for now and later, Oath of the Gatewatch is my pick. Displacer, Mimic, Matter Reshaper, Thought-knot, Reality smasher are all amazing on their own (okay mimic sorta needs dedicated eldrazi, but then it can be good). Otherwise, digging into BFZ is the 2nd best choice since you can put together red/black or blue/black (or red/blue/black too) eldrazi since it features lots of options at common and uncommon. And it has Ulamog incase reanimation is you're kind of strategy.