Actually, the idea is to have any one of the eldrazi (preferably That Which Betrays) hit the field turn three, four if you're running slow. Turn two is the earliest (1:
Swamp,
Memory Sluice yourself, 2:
Swamp,
Exhume /
Animate Dead). I run twelve eldrazi to increase the chances of hitting them with
Memory Sluice (it's currently at about 50% with a first-turn
Memory Sluice, which is actually lower than I'd like).
Typically, however,
Memory Sluice is not in a viable opening hand. More commonly, I run twelve eldrazi because it raises the chances of seeing an eldrazi in your opening hand to 90%--actually, more like 93%, because you should
always take the draw. A regular game goes thus: 1: no action, discard eldrazi, 2:
Swamp, 3:
Swamp,
Exhume /
Animate Dead. This works excellently against pretty much any deck that does not ramp like crazy, as annihilator 2 or 3 will lock down most opponents early game. Decks that
accelerate fast enough (for instance, I have a UG infect deck that pumps
Glistener Elf as its primary mechanic) can beat this curve, but most slower decks cave to it in all the right ways.