Haystack

{2}, {T}: Target creature you control phases out. (Treat it and anything attached to it as though they don't exist until your next turn.)

Meren of Clan Nel Toth

Whenever another creature you control dies, you get an experience counter.
At the beginning of your end step, choose target creature card in your graveyard. If that card's mana value is less than or equal to the number of experience counters you have, return it to the battlefield. Otherwise, put it into your hand.

Spawning Breath

Spawning Breath deals 1 damage to any target. Create a 0/1 colorless Eldrazi Spawn creature token. It has "Sacrifice this token: Add {C}."

Akul the Unrepentant

Flying, trample
Sacrifice three other creatures: You may put a creature card from your hand onto the battlefield. Activate only as a sorcery and only once each turn.

Brood Monitor

Devoid (This card has no color.)
When this creature enters, create three 1/1 colorless Eldrazi Scion creature tokens. They have "Sacrifice this token: Add {C}."

Minthara, Merciless Soul

Minthara has ward {X}, where X is the number of experience counters you have.
At the beginning of your end step, if a permanent you controlled left the battlefield this turn, you get an experience counter.
Creatures you control get +1/+0 for each experience counter you have.

Eyeless Watcher

Devoid (This card has no color.)
When this creature enters, create two 1/1 colorless Eldrazi Scion creature tokens. They have "Sacrifice this token: Add {C}."

Deathless Behemoth

Vigilance
Sacrifice two Eldrazi Scions: Return this card from your graveyard to your hand. Activate only as a sorcery.

Smothering Abomination

Devoid (This card has no color.)
Flying
At the beginning of your upkeep, sacrifice a creature.
Whenever you sacrifice a creature, draw a card.

Eldrazi Linebreaker

Devoid (This card has no color.)
Trample
At the beginning of combat on your turn, target creature you control gains haste and gets +X/+0 until end of turn, where X is the number of Eldrazi you control.

Brood Birthing

If you control an Eldrazi Spawn, create three 0/1 colorless Eldrazi Spawn creature tokens. They have "Sacrifice this token: Add {C}." Otherwise, create one of those tokens.