Artifact â Equipment
Equipped creature gets +3/+1 and must be blocked by an Eldrazi if able.
The defending player, not the attacking player, chooses which Eldrazi blocks the equipped creature.
Only one Eldrazi is required to block the equipped creature. Other Eldrazi and non-Eldrazi creatures may also block that creature, and are free to block other creatures or not block at all.
One creature equipped with multiple Slayerâ€™s Cleavers only requires a single Eldrazi to block it.
If each Eldrazi that could block the equipped creature is tapped or is affected by a spell or ability that says it canâ€™t block, then none of them block. If thereâ€™s a cost associated with having each of those creatures block, its controller isnâ€™t forced to pay the cost, so they donâ€™t have to block in that case either.