Nimrod attempted to follow Rachel into the past, but undershot his destination by about twenty years. Realizing his mistake
Nimrod searched for the Maker, an alternate version of Forge. Nimrod found him in Eagle Plaza with his wife Storm their daughter Orora and son Naze. Nimrod quickly killed Storm then held Orora hostage and forced this alternate Forge to create a time machine. However, the time machine Forge created damaged Nimrod so that he arrived at his destination offline.
Nimrod arrived in New York City and saved and befriended Jaime Rodriguez. He assumed the identity of Nicholas Hunter, whom the public perceived was an armored vigilante hero. 
Nimrod fought against Juggernaut. On a outing to a diner, some thugs who attempt to rob the place. Nimrod simply changed into his true form and incinerated the two crooks on the spot. As the two left the diner, Nimrod was hailed as a hero. He battled the X-Men and the Inner Circle of the Hellfire Club. On both occasions he was forced to withdraw, although he killed and incapacitated several of his opponents in his second battle.
Eventually Nimrod came in contact with the remains of the Master Mold which forced the two entities to merge. The entity battled the X-Men, but was sent to Siege Perilous, from where it eventually returned as Bastion.
Ghost in The Machine
Before turning into Bastion, Nimrod created and downloaded a self-aware program copy of himself into a military base that acted as a sleeper virus that awaited the opportunity to access a Sentinel development program it could use to re-create itself to insure his survival and to fulfil its imperative to save humans by exterminating mutants. When Cable and his X-Force entered the base Nimrod activated himself then spontaneously create a body, replete with advanced weaponry and defenses to destroy the mutants intruder. Nimrod, despite not being advanced as before proved to be strong enough to hold his ground against the X-Force and even Cable.
However, the sonic scream of Siryn temporarily disabled him and while the robot worked to compensate and adapt itself to the attack, Cable linked himself into Nimrod using his techno-organics and the mind of two doctors using telepathy. Inside Nimrod's mind the trio learned the truth and also learned that Nimrod believed that if he was created before his time he can save the millions that will die in the 25 years of war that will happen in the future. However, after being asked to determine how many humans will die if he was created before its time, the result was incalculable and so Nimrod deactivated itself. The robot’s central neural net was removed and given to X-Force while the scientists kept the body to study its defensive systems and alloys.
Nimrod was damaged during the transport, and he appeared inactive to William Stryker in an abandoned church two years before M-Day. Stryker then reformed his Purifiers and used Nimrod's knowledge and weaponry. Eventually Nimrod activated, and again searched for Forge in Texas in order to repair it's time machine, this time threatening to kill Storm. Forge tricked Nimrod by building it another body, which trapped Nimrod's programming under another program. However due to injuries sustained in an accidental battle against the New X-Men, Nimrod reclaimed control. It then continued to battle the New X-Men until Nimrod's time machine was activated and it disappeared into the past.
Matthew Risman became the new leader of the Purifiers and reclaimed Nimrod's original robotic shell from the wreckage of Forge's stronghold. They were unable to restore his power until new member, Eli Bard told them that Nimrod had been to their timeline prior to his most recent appearance to William Stryker. They learned about how Nimrod had become Bastion and then stole the head of Bastion which was being kept in a S.H.I.E.L.D. facility. The Purifers reattached the head of Basion with the body of Nimrod--giving new life to Bastion.
Bastion personally confronted Hope Summers, Rogue and Nightcrawler, leading to the death of the latter. Bastion appeared to be reverting more and more to fully being Nimrod. Some time later, Bastion unleashed an endless horde of Nimrods from an unknown future to destroy the X-Men. However X-Force, Cypher and Cable go to that future and destroy the Master Mold controlling them. Bastion became Nimrod again but is destroyed by Hope.
The chest and head of Nimrod were exhibited in the Cavern-X facility. Deathlok identified it as version 32.1 and the possibility for its future to come to be is 1.34%.
During a brief glimpse three months into the future, Scarlet Witch, Havok and Sunfire flee from a new model of Sentinel. Havok referred to the machines as Nimrod units, and mentioned that they were built by Tony Stark.
Nimrod is a highly advanced robot, and as such all his powers are functions of his inbuilt systems. The full range of his powers are unknown, as he is able to reconfigure systems to defeat known opponents. The materials Nimrod is constructed of are highly resistant to damage even by superhuman beings. He can alter his size and appearance to that of a human, which is used as a cover identity. 
Damage to Nimrod's armor and systems can be automatically repaired to an unknown extent. He has direct control over all parts of his structure, perhaps to the molecular level. An extension of this power is the rearrangement of internal parts to better use his functions and weapons.
Mutant and superhuman sensors and detectors contained within Nimrod's arms and head allow him to locate and analyze beings' extraordinary powers, and determine modifications that need to be made to his own abilities. He is capable of countering most powers that are used against him on separate occasions, continually learning how to defeat opponents that escape him. 
The weapons and defenses Nimrod contains have a wide range of applications. He can project concussive, plasma and disintegrating blasts, manipulate magnetic energy to levitate iron and steel, and generate force-fields about himself. 
He can teleport, which can be used even when he has suffered severe damage.
The possibility exists that the Nimrod that becomes Bastion and the Nimrod that battled the New X-Men were two different Nimrods. However, the similarities between the two are uncanny, leading most to believe that they are the same entity. Whether or not this is true, remains to be confirmed.
Nimrod is named after the Biblical figure Nimrod, great-grandson of Noah, defined by the King James Version Bible in Genesis 10:8-9 as as a "a man of power in the earth and mighty hunter before the Lord."