Sentinel 3

Vigilance, Menace, Bastion (Creatures with
Bastion can only be blocked by an Artifact
Creature.)
Backup 3: When Sentinel 3 dies, three more
take it's place.
Ambush X: Up to X creatures you control
attack target player. It can't be blocked.
Can't be used more than once.
"Join, Conquer, Destroy."